Patrizia

PHYSICS AND TONAL DESIGN IN PIPE ORGANS AND AIR-JET MUSICAL INSTRUMENTS

INTRODUCTION

Tones of air-jet instruments are considerablyaffected by the jet velocity profile which depends onthe geometry of the flue channel and flue exit.However, there are very few reports that givequantitative measurement of the velocity profile orsome correlation between the flue geometry and thevelocity profile. Our aim is to make the comparison ofthe velocity profiles resulting from some fluegeometries typical of air-jet instruments such as thepipe organ, flute, and recorder.

MEASUREMENT

The flue geometries used in our experiment areillustrated in Fig. 1 . The “long” has a long and uniformflue channel and flat exit. Such a flue is often used inexperimental organ pipe models. The “chamfer” hasthe same flue geometry except for the chamfer on thelower side of flue exit. The flue geometry of “short”may give a simplified model of shakuhachi or fluteplayer’s lips. The “organ5” and “organ1” are differentfrom each other in the thickness of languid (5mm and1mm). The flue height 2h is 2.2mm in all of the fluegeometries throughout the measurement. The velocity profile is measured by using a hot-wire

anemometer when the probe is precisely dislocatedwith a 3-D adjustable traverser. The measurementparameters were set as follows :

Initial center line velocity (U00) 10, 20, 40, 50 m/sDistance from the flue exit (x) 2, 4, 8, 15, 25 mm

The transverse velocity profile of the jet was measuredfor the fixed U00 and x values.

RESULTS Figure 2 shows the profiles of the “long” and“short” obtained at the same experimental condition(U00= 10 m/s, x = 4 mm). These profiles are wellapproximated by

where U0 defines the centerline jet velocity and bthe jet half-thickness. The profile from the “long” flue

Measurement of Velocity Profiles of the Jets Issuing fromSome Flue Geometries Typical of Air-Jet Instruments

Shigeru Yoshikawa and Keita ArimotoDept. of Acoustical Design, Kyushu Institute of Design, Fukuoka, 815-8540 Japan

Air-jet musical instruments may be categorized by the geometry of flue channel and flue exit: The flue of metal organ pipesis simply modelled by a vertical plate and a horizontal languid (such a flue is called "organ" here). The flue made by flute orshakuhachi players may be modelled by two thin plates corresponding to player's lips (called "short" because of shortchannel length). Contrary to this "short" flue, a "long" flue consisting of two long plates has been used for experimentalorgan pipe models. The recorder flue can be modelled as a long flue with a chamfer on the edge of the lower plate (called"chamfer"). The measurement of jet velocity profile was carried out on these flue models without using pipe resonators. Theprofile was measured at the distances of 2 to 25 mm from the exit when the initial jet velocity was varied from 10 to 50 m/s.The flue height was 2.2mm throughout the measurement. The profile difference between the “short” and “long” flues isdistinctive as inferred from the top-hat and Poiseuille profiles at the exit. The profile from the "chamfer" flue tends tochange from the "long"-type profile for lower jet velocities to the "short"-type one for higher velocities. The "organ" flueindicates an asymmetric profile for shorter distances from the exit. The "organ" jet directs downwards when the languid is 5mm thick, while directs upwards when it is 1 mm thick. The experimental results are compared with the theoretical Bickleyprofile on a laminar two-dimensional jet and an empirical Nolle profile more squarish than the Bickley profile.

foot 2h 5mm

foot2h

5mm, 1mm

2mm1mm

foot2h

100mm98mm

(a) long

(c) chamfer (enlarged near the flue exit)

2h

(b) short

(d) organ5 , (e) organ1

Fig.1 Flue geometries used in our experiment.

)1(),3,2,1()/(sech)(),( 20 ⋅⋅⋅== nbzxUzxU n

has n=1 and shows the so-called Bickley profile; the“short” flue has n=3 and shows the so-called Nolleprofile. The difference between the profiles is inferredfrom the difference in channel flow at the flue exit, asillustrated in Fig.3 . It may be supposed that thechannel flow has reached the following Poiseuilleprofile at the flue exit of the “long” flue.

On the other hand, the top-hat profile may be assumedat the flue exit of the “short” flue. The abovementioned difference between the velocity profilesfrom the “long” and “short” flues is held up to x= 8mm and U00 = 20 m/s (the Reynolds’ number Re≈3000). Figures 4 and 5 indicate the profile difference at x=8 mm between five flue geometries for U00 = 20 m/sand 40 m/s, respectively. We may easily recognize theindividuality (or separation) of the profiles (althoughthe profiles of “chamfer” and “organ1” are partlyoverlapping for |z| > 1mm) when U00 = 20 m/s.However, the profiles seem to be divided into two, the“long” profile and the other profiles when U00 = 40m/s. Also, all the profiles at x ≥ 15 mm approach tothe Bickley profile regardless of flue geometry. Somecharacteristics typical in other flue geometries aresummarized as follows;(1) The behavior of the jet from the “chamfer”

changes from the “long”-type profile (cf. Fig.4) to the“short”-type profile (cf. Fig.5) when the initial jetvelocity U00 increases from 20m/s to 40m/s.(2) The jets of “organ5” and “organ1” do not runstraight along the x axis as illustrated in Figs.6 and 7.More interestingly, the “organ5” jet gradually deviatesdownwards (about –10 degrees) , while the “organ1”jet deviates upwards ( about 10 degrees) .(3) Initial velocity profiles (at x= 2 mm) are alsodifferent between the “organ5” and “organ1” asindicated in Figs. 6 and 7. The “organ5” profile isasymmetrical and distorted, although it becomessymmetrical as the jet travels downstream. The“organ1” profile is symmetrical and it is close to thetop-hat profile rather than the Nolle profile.

CONCLUSIONSVelocity profiles of the jets issuing from five kinds

of flue geometries were measured and compared. Theindividuality of five profiles was recognized in therange of 10 ≤ U00 ≤ 20 m/s and 2 ≤ x ≤ 8 mm.When U00 was increased to 40 m/s, four profilesexcept for the “long” one tended to make up one group,which may be roughly represented by the “short” one.Finally, all the profiles at x ≥ 15 mm approached tothe theoretical Bickley profile. Also, significant effectsof the languid thickness were recognized from the“organ1” and “organ5” profiles.

)2(/))((),( 2220 hzhzhxUzxU ≤−=

Fig.2 Velocity profiles of “long” and“short” for U00 =10 m/s and x=4 mm .

Poiseuille profile

top-hat profile

Fig.4 Velocity profiles for U00 =20 m/s and x= 8 mm.

Fig.3 Channel flow at the flueexit of the “long” and “short” flues.

Fig.5 Velocity profiles for U00

=40 m/s and x=8 mm.Fig.6 Velocity profiles of “organ5”for U00 =20 m/s and x=2, 8, 15 mm.

Fig.7 Velocity profiles of “organ1”for U00 =20 m/s and x=2, 8, 15 mm.

Can wall vibrations alter the sound of a flue organ pipe?M. Kob

Institute of Technical Acoustics, Technical University Aachen, D-52056 Aachen, Germany

Thepredictionof changesin theperceivedsoundof a blown pipedueto wall vibrationsis madedifficult by themultitudeof interac-tions. Excitation,shape,andsoundradiationof structuralmodesdependon a numberof parameterslike material,voicing technique,geometryandfixing of the pipe. This article presentsexperimentalwork on comparisonof vibrationsandsoundradiationfrom atin-rich pipein two cases:with dampedandundampedwall vibrations.It wasfoundout thatchangesin soundpressurelevel atcertainfrequenciesin thespectrogramcoincidewith eigenfrequenciesof bothair modesandstructuralmodesandthussupporttheassumptionof modecouplingbeingresponsiblefor soundchanges.

INTRODUCTION

Although most organ builders agree to organ pipe vi-brations being audible, this is in contradiction to manyexperiments that were carried out on modern organ pipes(for an overview, see [1]). A reason why this questionis not easy to answer is the multitude of parameters (e.g.foot pressure, voicing) and boundary conditions (e.g. pipesupport, temperature) that are difficult to control duringan experiment. In addition, modern flue organ pipes arerather thick-walled compared to pipes of the 17th or 18th

century.This work presents some measurement results indi-

cating that eigenmodes of the air column, further calledair modes, and eigenmodes of the pipe body, structuremodes, are likely to interact at some frequencies.

METHOD

Several experiments have been carried out (for details,see [1, 2]) for measurement of the air modes and structuremodes of the same pipe under two different conditions.For detection of the structure modes the pipe was inves-tigated either with walls covered by a removable, heavydamping layer or without layer. The air modes were iden-tified by insertion of a paper covered stick into the aircolumn inside the pipe. In both cases damping of the res-onances by 10 dB could be achieved.

Transient sound

At first the pipe was blown and the sound pressure wasrecorded.

Figure 1 shows the spectrograms of the pipe in twocases. For sake of better visualization, the harmonicshave been removed. To the left the undamped case isshown. Clearly several clouds are visible during thebuild-up of the sound. The sound of the damped pipe is

shown to the right. In this spectrogram, the clouds are stillpresent but the sound pressure level at certain frequencieshas been reduced by approx. 10 dB at 1250 Hz, 1550 Hzand 1800 Hz in the first 100 ms of the sound. Smallerdifferences between the damped and the undamped pipesound can be observed in the stationary part of the soundat those frequencies.

Stationary sound

As a second approach the pipe was mechanically ex-cited with a shaker at the labium (c.f. Fig. 2). The soundpressure at the upper (passive) end of the pipe has beenrecorded and the ratio to the applied force has been calcu-lated. For this frequency response functions (FRF) fourcases have been investigated: damped/undamped wallsand damped/undamped air column.

In a 3rd experiment, the eigenmodes of the pipe bodyhave been determined from laser velocimetry on the bodyof the mechanically excited pipe and subsequent modalanalysis. The results are compared to finite element cal-culations (FE). The measurement results are listed in Ta-ble 1.

Table 1. Comparisonof resonancefrequencies(in Hz) fromcal-culations(calc.)andmeasurements(meas.).

Structure modes Air modes

FE calc. Laser meas. FRF meas. FRF meas.

A 829 841 850 896B 1226 1241 1263 1209C 1514 1500 1516 1524D 1863 1853 1865 1840

0

500

1000

1500

2000

2500

50 100 150 200 250 300

−40 −20 0SPL [dB]

t [ms]

f [Hz]

Hanning window width: 92.8798 ms

Overlap: 2.9025 ms

0

500

1000

1500

2000

2500

50 100 150 200 250 300

−40 −20 0SPL [dB]

t [ms]

f [Hz]

Hanning window width: 92.8798 ms

Overlap: 2.9025 ms

FIGURE 1. Spectrogramsof theundamped(left) anddamped(right) pipewithoutharmonics.

Amp.

Amp.

A/D

D/A

PCwith

Monkey Forest

Shaker

Force

PressureMic.

Pip

e

LaserVibrometer

Velocity

FIGURE 2. Set-upfor theFRFmeasurements.

DISCUSSION

The wall vibrations appear to affect only a small fre-quency range (Modes A-D between 800 Hz to 1900 Hz,as presented in Table 1). Since the resonance frequenciesof the structural modes are similar to the eigenfrequen-cies of the air modes, the coupling theory is supported.Perceptually, the differences are very small1.

In the last two years, some more experiments havebeen carried out that seem to support the organ builders.Effort has been made to explain the nature of the couplingbetween air modes and structure modes and the hypothe-sis of pipe vibrations being audible. In [3] a mathematicalapproach to the theory of coupling in a simplified musi-cal instrument is presented. Nederveen [4, 5] explainsthe coupling as a change of the compliance of the air that

1 Sound examples and color pictures can be found on the Internet athttp://www.akustik.rwth-aachen.de/˜malte/pipe.

is bounded by an elliptical tube, vibrating in a twistingmode. Miklos and Angster [6] observed subharmonics inthe spectrum and deduced periodic wall stiffening fromthe non-linear effect caused by pressure fluctuations in-side the pipe. However, more experiments should vali-date these coupling theories.

ACKNOWLEDGMENTS

The author wishes to thank Michael Vorländer andMendel Kleiner for the opportunity to participate in theGOArt project. The discussions with Vincent Rioux, Pe-ter Svensson and Wolfgang Kropp were invaluable.

REFERENCES

1. M. Kob,ACUSTICA � acta acustica 86, 642-648(2000).

2. M. Kob,ACUSTICA � acta acustica 86, 755-757(2000).

3. F. GautierandN. Tahani,Journal of Sound and Vibration213, 107-125(1998).

4. C. N. NederveenandJ.-P. Dalmont,“Experimentalinvesti-gationsof wall influencesonwoodwindinstrumentsound”,in ACUSTICA � acta acustica 85 Suppl.1, 1999,S76.

5. C. N. NederveenandJ.-P. Dalmont,“Influenceof Wall Vi-brationsonOrganPipeSoundLevel andPitch”, in Abstractbook of The Physics Congress 2000 � Physics of MusicalInstruments (POMI), Brighton,2000,54-55.

6. A. Miklos andJ. Angster, “Linear andNonlinearWall Vi-brationsof OrganPipes”,in Abstract book of The PhysicsCongress 2000 � Physics of Musical Instruments (POMI),Brighton,2000,54.

������������ ��������������� ���� ������ ������ ����! "���$#�� �%���'& ��& �(�#�)�*��+ ,��%#���$-/.�� �$& �0 �� ���'.��1-/�$& �(�#�)

2%3547698*:<;�=?>@;�=A6CBED�FHG$3IFHJLK"6CMEDE;�N�O

OLPHQ?RLSUTWV�XQLVCYZXSU[\5]$^`_bacR(dfeg[ihTcjkeg[bVmlmn"SodLp"arqs_bl`tvuoaxwLeg[k_kaxV�XQLV"PZ[yeza{jgSU[mqs|~}Ieg[b�7Qsuou9l{}Ieg[�dfeg[bl��9V�[g���s|��������z��P�[�eza{jgSU[mqs|� eg[b�7Qsuo^

�m�f�?�k�����W�`�g���W�����������������k�i�r�����g�������g�"���r�k f�r���¢¡y�?�$£f�¤���r�����i¥5�¤��¦�§��?�f��¦����$£'�`�L¡k���"�¨����¡y���g���7�U���¨©ª����§��k£'¥5�¤��¦�¦��g�¨«{¥5�¤��������k§��?§��y�¨�¨ I¬x­¯®/°²±v�g�$£����g�¨���W¡k�W�³�W§´�����<�?�k�W�L¡k�W§��y�¨�¨ 7¬¶µ���·²±�¸L¹E¦��<�`�L¡b�g���¨����¡y�~¡b���´ºU�5©ª�g��§��b£��W�I�¨��¡�¦I�²¥"�k �����¡k�������r�5�����¦��E�������5�g��������£¼»¯½f­<¾?¸Z¿����H��¦��5��¡y�?�������W¡5À$�k�r£��7Á{���k�¨�?������¡y�kÂ��yÃÄ�k¡y�v�W�v��º��¨�y���`�k£oÅZ¹E¦��5�k�`�k��¦��g��§������W¡k�v�g���5�¨���������k�¨�¨�b£�������!�!©x�g¡y�����"�m¥E�!�W�I��¦��<�f���k�¨�¨�����³��§����W�¤���$£f�<���$£f�y�E¡k���¨�����W�¼¡y�?�$£f�¤���r�����k¸H�m�~�W�E�¨¦��b¥5�´��¦$�g�~��¦��¯�`�k�W�L¡k�¤�� ´�g©C��¦���Æ����"�W�"���¨���?�����¤ �W��¡y���b�g�¨�b£Ç£f�����W������¦��<�`���¨����È��¨¦��b£�£��W����g�"��¦��³�r��º��W��§7¸�¹E¦��²§��?�f��¦´���y�¨�?�$�g��¡k�³¡y���b�g���y�5���¦����¨�<�¨¦��¤©É�5�g©@��¦��<�`�k�W�L¡k�¤�� ´�U�b�g½U¸¹E¦����?º��¨�y�����g���W�?���Ê�g���!¡y���?�¨�³¡�¦��k¡�½?�b£ÇºL Ëµ���·�¥5¦��r¡�¦/£��W�¨���r�k f�<��¦�����¦��i£f�y�����W�W�³�g©v��¦����`���¨���yÈ7��ºU�z�`����¦����r��º��r��§7¸5®Ì�¤��¦A����yÈs���y���$�g�W�W ¼£s���r�?�k�7�g¡k�?�������r¡k���CÀ��k�r£I��¦��³�`�k�W�L¡k�¤�� IÀ$�k�r£I���b�z�<ºU����¥E�y�k�7�r��º��r��§Í����£I�$���²�W�5§��b���¨�f���b£I©É���<¡k�?§����g���W�¨�?�o¸

MOUTH PISTONLIPSlight sheetoptics

light sheet

embouchuremicrophone 2

head flue

1 cm

air inlet

Î~ÏÉÐfÑÄÒyÓ'ÔfÕ�Ö �y��������©5��¦����yÈf�U�y���W§��k�L�i�g�i�s�W�y¥E�k£�ºs /��¦��µH�m·×¡b�g§��y���i�g�W�?������¦��³�$�f���?¸

ØzÙ'Ú´ÛAÜAÝ¢Þ'ß¼Ú´Ø�ÜËÙà²áÄÓÊâoÑoÓ!ÏÉãoä�åyÒ�ÑoæÇÓ�ã�åyä¯çfÒ�Ó!Ïcã$èfÓ?ä�åyÏcÐ�çLåyÓ�é7ä�ÏÉãoêgÓ!ë�ÑÄÏråyÓ

çAå�ÏÉæÇÓ�ì�ä�Ó�ÓIí¶î�ÒÏÉãoä�åyçfãoêzÓ�ïrÔgð�ÕIñUò9Ó?êzÏcó9êgçfôcôÉõ�å�áÄÓÇòCî�äyä�Ïcö÷ ÏÉôÉÏrå�õ%îsí�ç'æ7îfÑÄå�á�ÒyÓ�ä�îfãoçfãoêzÓËÏÉãÌâoÑÄå�Ó�äIÏÉäÇçféoéUÒ�Ó?ä�ä�Ó�éÏÉã0òoÑ ÷ ôÉÏÉê�çLå�ÏÉîfã×ï øLð�ÕÇà²áÄϪä�Ïcã$èfÓ?ä�åyÏcÐ�çLåyÏcî�ã�ÏÉä�Ð�ÑÄϪéUÓ�é ÷ õåyáÄÓ�í¶î�Ò�æËçsã�åkä"ÏcãAå�áÄÓiä�òCÓgÓ?êká/çfä5å�áÄÓèfîUêgçfôÄå�Òkçfêzå5í¶îfÒyæËäç7ÒyÓ�ä�îfãoçså�î�Ò�çLå!ç ÷ îfÑÄåIÔ´ùUú�û�Õ³à²áÄÓIòÄÒ�î�ò9Ó�Ò�åyÏcÓ?äÊîsíEåyáÄÓü ÓgåÑoä�ÏcãoÐAå�áoÓ¼áÄîfå�ö�ýÊÏcÒyÓ¼çfãÄÓgæ7î�æÇÓgå�Òyõ(ç�ä!ý³ÓgôÉôEçfä!þ¯ÿ��Ϫä²Ïcã$è�Ó�ä�å�ÏÉÐ�çLåyÓ�éAçfôcî�ãÄÐÇýÊÏråyá¢åyáÄÓ´ä�ò9Ó?êbå�ÒkçsôZéUϪä�å�ÒyÏ ÷ ÑÄå�ÏÉîfãîfí~ä�îfÑÄãoé�Õ

�������iÛ/Ø��Ù'Ú��� ����iÚ´Þ����¢Ù'Ý Û����HÞ� @Ú��ÎÄî�Ò'å�áÄϪä0Ïcã$èfÓ?ä�åyÏcÐ�çLåyÏcî�ã åyáÄÓ�âoÑÄå�Ó�Ϫä�î�ò9Ó�Òyçså�Ó?é�çså

ç ü Ógå(ä�ò9Ó�Ó�é�îsíAÔ��0ö����*æ��säAýÊÏcå�á åyáÄÓ'óoãoÐfÓgÒyÏÉãÄÐÌîsí���Ëêzî�Ò�ÒyÓ�ä�ò9î�ãoéUÏÉãÄТå�îÌÔfÔ � �(ú�û'Õ/à²áoÓ ü ÓzåIϪä�í¶îfÒyæ7Ó�é÷ õ0ç'âoÑÄÓ ÷ Ózå�ý³ÓgÓ�ã�êgçsÑÄåyêkáÄî�Ñoê7ôcÏÉòoä¼çsãoé*ÏÉã�å�ÓgÒkçfêzåyä´çsåç éUϪä�åyçsã9êzÓ�îfí!�ÄÕ �sæÇæ ýÊÏcå�á�å�áoÓ�ôÉç ÷ ÏÉÑÄæ�Õ à²áoÓ�çsÏÉÒϪä/Ð�ÑÄϪéUÓ�é�åyáÄÒyîfÑÄÐ�á çÌåyÑ ÷ Ó%ýÊÏcå�á ç�æ7îLè`ç ÷ ôÉÓ�òÄϪä�åyîfãÒyÓgòÄÒyÓ�ä�Ógã�åyÏcãÄÐ�å�áÄÓ*æ7îfÑÄå�á�çsãoé èfîUêgçfôiå�Òkçfêbå?ìiä�ÓgÓ%óoÐföÑÄÒyÓ%ÔfÕ�à²áÄÓ�æÇî�ÑUå�á�ÒyÓ�ä�îfãoçfãoêzÓ¢îUêgêzÑoÒyä7çLåAç ÷ î�ÑUå'Ô"�

Î~ÏÉÐfÑÄÒyÓÇøÄÕ µ����y�¨�¨�����!�¨�r���$�g�H�g©���¦��!¦$�g��§������W¡k�³���²��©ª����¡y«���r���7��©Z��¦��²�W�k���g��¦7��©C��¦��²§�������¦¼���y�¨�?�$�z�����b¸

êgæ ôcÓ�ãÄÐsåyá�æ7Ó�çfä�ÑÄÒyÓ�é�ýÊÏcå�á'åyáÄÓ ÷ ÑÄÏcôªé$ö�Ïcã�æÇϪêzÒyîfòoáÄîfãÄÓ# æ7ÏÉêgÒ�î�òÄáÄîfãoÓ�ø�$bÕ5à²áÄÓ´ä�îfÑoãoé/òoÒ�Ó?ä�ä�ÑÄÒyÓîfíHå�áoÓ�âoÑUå�Ó�Ϫäæ7î�ãÄÏråyîfÒyÓ�é ÷ õ¢çÇæ7ÏÉêgÒ�î�òÄáÄîfãoÓiÏÉãoä�ÓgÒ�å�Ó?é¢ç ÷ î�ÑUå%���¼æ7æÏÉã�å�î�å�áÄÓ(îfòCÓgã�Ó�ãoéÌîfíÊå�áÄÓ/âoÑUå�Ó ÷ î$éÄõfÕ0à²áoÓ¢ä�õ$ä�å�Ó�æõ$ÏÉÓgôªéÄä/ç�òÄÒ�Ó?ä�ä�ÑÄÒyÓ'çsæ7òÄôÉÏråyÑoéUÓ�îfíIø&�'�Ìþ"ç*çsåAå�áÄÓ ü Ózåä�òCÓgÓ�é(îfí³Ô ��æ��Lä�Õà²áoÓ!ä�òCÓ�êzå�ÒkçsôCéUÏÉä�å�ÒyÏ ÷ ÑUå�ÏÉîfã7Ϫä5æ7Ó�ç�ä�ÑoÒ�Ó?éÇç�ä5ç�í¶ÑÄã9êbå�ÏÉîfãîfíÄå�áoÓ³æ7î�ÑUå�á¼Ò�Ó?ä�î�ãoçLåyîfÒHôÉÓgãoÐså�áHÕ~à²áÄÓ³òCÓ�çsù�èLçfôcÑÄÓ?ävçfÒ�ÓçfÒ�ÓòÄôÉîså�åyÓ�é/Ïcã/óoÐfÑÄÒyÓiøIçfä³ç�í¶ÑÄã9êbå�ÏÉîfã¢îsí�åyáÄÓéÄÏÉä�åyçfãoêzÓîfí�òÄϪä�åyîfã7í¶Òyîfæ å�áÄÓ!âoÑÄÓfÕ)(!ãËÏcã�å�Ó�Ò�Ó?ä�åyÏcãoÐ+*�ÒyÓ�ä�îfãoçfãoêzÓ",Ó.-CÓ?êbå´Ïªä�ä�Ó�Ógã0Ïcã0å�áÄÓËÒyÓ�éÄÑoêbåyÏcî�ã�îsí<å�áÄÓ7òÄÒyÓ�äyä�ÑÄÒ�Ó7çsæÇöòoôcÏcå�ÑoéÄÓ'îsíiå�áÄÓ'ä�Ó�êzî�ãoé×çsãoé�í¶îfÑÄÒ�å�á×áoçfÒ�æ7îfãoÏÉê�ä ÷ õ�çí{ç�êbåyîfÒ0/�øAçsã9é�ä�î�æ7Ó¼éUϪä�òCÓgÒkä�Ïcè�Ó¼éUÓ�ò9Ó�ãoéUÓgã9êzÓ¼í¶îfÒå�áÄÓîUéÄé�áoçsÒyæ7îfãÄϪêgä�Õ*ÿ�åÇϪäÇù$ãÄîLýÊãÌå�á9çLå7å�áÄÓ�ä�å�ÒyÓgãÄÐfå�á�îfíÓ�èfÓ�ã�áoçsÒyæ7îfãÄϪêgä�éÄÓgòCÓgãoéÄävîfã�åyáÄÓ¯ôªç ÷ ÏcÑÄæ�î&-Zä�Ózå�Õ~ú�îLý²öÓ�èfÓ�Ò5ç�ä�åyÒ�î�ãÄÐ�è`çfÒ�ϪçLåyÏcî�ãIîfí9åyáÄÓ�Ó-@Ó�êzå5ÏÉä5ãÄîså5î ÷ ä�Ó�Ò�è�Ó�éZÕÿ¨ã'îfÒkéUÓ�Ò²å�îËÓ1ÄçfæÇÏÉãÄÓ´ç7òCî�äyä�Ï ÷ ôÉÓ´êgçfÑoä�Ó�îfí~åyáÄÓ´ä�ÑÄòUö

òoÒ�Ó?ä�ä�Ïcî�ã�ìfä�òoçLåyÏÉçfôoäyêgçsã9äEýÊÏråyá7ç�áoîså�ö�ýÊÏÉÒ�ÓÊçsãoÓgæ7îfæ7ÓzåyÓgÒçfÒ�Ó(åkçsùfÓ�ã çLåAç*ò9î�ä�Ïcå�ÏÉîfã�îfí�øÄÕ �0æ7æ éUϪä�åyçsã9êzÓ�í¶ÒyîfæåyáÄÓAâ9ÑÄÓfÕ�à²áoÓ ü ÓzåÇèfÓgôÉîUêzÏcå�õ�òÄÒyîsó9ôcÓAϪäIç`è�ÓgÒkçsÐ�Ó�é0îLèfÓgÒ

Î~ÏÉÐfÑÄÒyÓ!�ÄÕ ¹C�?�oÅ!·v�k�W�L¡k�¤�m ��g��I©ª����¡y���W�?���g©"���W§��?¸�2Ç�r£f«£��W�?Å!°¯§����W�¤���$£����©E��¦����¨�W�?�����~�g©5§��W¡y���?��¦��?���03¢¬x§�������¦���k�¨�?���g���g��±�©ª�g�����r���������U�?�¨�¤���W�?���ºU�y��¥~�k�k�Ì»54/�g�$£%»76g¡k§7¸8~���¨����§7Å"µ@���¨�W���W���/�g©���¦��"Æ��y�i¬x�?�U�k�Ë�:9L���g���k��±5����£Ë��¡k������«���W¡b���Ä¥"�b�`��¬ªÀ��r�W�b£¼�:9s���g���k��±v¥5�¤��¦Ëµ���·�§��b���¨�f���k§��k�L�b¸

æËçsã$õ7êzõUêzôÉÓ�ä³çsã9éËóÄå�å�Ó�é/ýÊÏråyá¢ç�;<Ϫêkù$ôcÓ�õËéUÏÉä�å�ÒyÏ ÷ ÑUå�ÏÉîfãHÕà²áÄÓ�êgÓgã�å�ÒkçsôoèfÓgôÉîUêzÏcå�õ´Ïªä¯ä�áÄîLýÊãËçfä~í¶ÑÄãoêzå�ÏÉîfãAîfí9åyÏcæ7Ó�ÏÉãóoÐ�ÑÄÒyÓ<�oÕ~à²áoÓgÒyӳϪäEåyáÄÓ�ç�ò9Ó?çsù´îfí@ç ÷ î�ÑUå�Ô"�>= í¶îfÒ¯ò9î�ä�ÏcöåyÏcè�ÓÊå�ÏÉæ7Ó�ä³çfä"åyáÄÓ ü Ógå<æ7îLèfÓ?ä5éUîLýÊã$ý²çsÒkéÄä"êzÒyî�äyä�ÏÉãÄÐ�åyáÄÓôªç ÷ ÏÉÑÄæ�ì<ä�ÓgÓ ÷ îså�å�îfæ òoçsÒ�åËîsí!åyáÄÓ(óoÐfÑoÒ�Ó�Õ×à²áÄϪäÇí{çfêzåê�çsã ÷ Ó(éUÓ?éUÑoêgÓ�é�çfôÉä�î'í¶Òyîfæ òÄÒyÓ�äyä�ÑÄÒyÓËæ7Ó�ç�ä�ÑÄÒyÓgæ7Ó�ã�åkäï �Lð�Õ~à²áoÓÊò9Ó?çsùIϪä¯çfòÄòÄÒyî�1UÏcæËçLåyÓ�é ÷ õÇç0?�çsÑoäyä�ÏÉçfãÇÏÉãËîfÒ�öéUÓ�Ò³å�îAë�Ñoçsã�åyÏrí¶õ/êká9çsãÄÐ�Ó�ä³Ïcã(òCî�ä�ÏråyÏcî�ã(çfãoé(áÄÓgÏÉÐfá�å�Õ)(äÏÉãoéUϪêgçså�Ó�é(ÏÉã(å�áÄÓ�óoÐ�ÑÄÒyÓ ÷ õ(çsÒyÒ�îLý�ä³çLåÊåyáÄÓ�ò9Ó?çsù¢ò9î�ä�ÏcöåyÏcî�ãAå�áoÓiêkáoçfãÄÐfÓýÊÏråyá/åyáÄÓ�òÄϪä�åyîfã/òCî�ä�Ïcå�ÏÉîfã/Ϫä³î ÷ è$Ïcî�Ñoäç�ä�åyáÄÓ¼æ7î�ÑUå�á0Ò�Ó?ä�î�ãoçsãoêgӴϪä!åyÒyç`è�ÓgÒkä�Ó?éZÕ@(äiÓ1Uò9Ó?êbåyÓ�éåyáÄÓIä�áÄÏríxåÏÉäêzîfÒyÒyÓgôªçLå�Ó?é/ýÊÏcå�á�åyáÄÓ´òÄÒyÓ�äyä�ÑÄÒ�Ó´çfæ7òÄôcÏcå�Ñ9éUÓîfíiåyáÄÓ�æ7î�ÑUå�á ÒyÓ�ä�îfãoçså�î�ÒAçfä/ê�çsã ÷ Ó0ä�ÓgÓ�ã�í¶Ò�î�æ åyáÄÓóoÐ�ÑÄÒyÓ��oÕñ$ÏÉãoêzÓ5éUÓgåyçfÏcôªäZîsí$åyáÄÓ ü Ózå~çsÒyÓEéÄÏBAAêzÑoôråvå�îÊÓ1$åyÒyç�êbå�ýÊÏcå�á

ú%CD(´ì?æ7Ó�çfä�ÑÄÒyÓgæ7Ógã�åkäZýÊÏråyáIþ5ÿ�� # ÿ:E�(×ñ$õUä�åyÓgæËä5$�çféoéÄäÏÉãUí¶îfÒyæËçLåyÏcî�ã�îfã´åyáÄÓ³èfÓgôÉîUêzÏcå�õ!ó9ÓgôªéZÕ~à²áoÓ<è�ÓgôÉî$êgÏrå�õ�òCÓ�çfùçfãoéAÏcåyä�éÄÓgòCÓgãoéUÓ�ãoêzÓ�î�ã/åyáÄÓ�æÇî�ÑUå�á�ÒyÓ�ä�îfãoçså�î�Ò¯ôÉÓgãÄÐfå�áϪä³Ò�Ó�òÄÒ�îUéUÑ9êzÓ�éAÏcã/å�áÄϪä²Ó1UòCÓgÒyÏcæ7Ógã�å?ÕF(äÊä�Ó�Ógã¢Ïcã/óoÐfÑÄÒyÓG9ìfÒyÏcÐ�á�å³ä�ϪéUÓfìfå�áÄÓiéUîLýÊã$ý³çfÒyéoäEæÇîLè$ÏÉãÄÐ ü Ózå³òÄÒyî$éÄÑoêzÓ?ä¯çä�å�ÒyîfãÄÐèfî�Ò�åyÓ1Zì?å�á$ÑoäEÓ1UòÄôªçsÏÉãÄÏÉãÄÐ�í¶Ó?çLåyÑÄÒ�Ó?äví¶îfÑÄãoé¼ÏÉãIåyáÄÓú%CD(´ÕZà²áÄÓËþ5ÿ�� ä�Ózå�Ñoò�Ϫäiç ÷ ôÉÓIåyî(éUÓgå�Ó?êbåiå�áÄÓËçfêgîfÑoä�öåyÏÉê�è�ÓgôÉîUêzÏcå�õAóoÓ�ôÉéZÕHC Ïcå�áoîfÑUåiîfòCÓgÒkçLå�ÏÉãÄÐ7åyáÄÓ�âoÑUåyÓIÏcå!ϪäêgÒ�Ó?çLå�Ó?é ÷ õ*ç�ä�òCÓ�çfùfÓgÒ�`áoîfÒyã*ä�õUä�åyÓgæ êzî�ÑÄòÄôÉÓ�é*åyî�åyáÄÓî�ò9Ó�ã Ógãoé�îfíiåyáÄÓ�â9ÑUå�Ó ÷ îUéUõ�ÕI(³åAå�áÄÓ%ä�çfæ7Ó�ä�î�ÑÄãoéòÄÒyÓ�äyä�ÑÄÒ�Ó�çsæ7òÄôÉÏcå�ÑoéUÓ�åyáÄÓ�èfÓ�ôcîUêzÏcå�õÌóoÓ�ôÉé×Ϫä7æ7Ó�çfä�ÑÄÒyÓ�éçså³åyáÄÓ�ôªç ÷ ÏÉÑÄæ�ì9ä�ÓgÓióoÐ�ÑÄÒ�Ó�G9ìÄÒ�ÏÉÐfá�å�ä�ÏÉéUÓ�Õ5à²áÄÓ�ÓgèLçfôcÑoçsö

Î~ÏÉÐfÑÄÒyÓ�G9ÕKJ �W�?�¨�y«{���'��©"��¦����?�k�W�L¡k�¤�� /À$�k�r£(§��b�g�¨�����b£¢ºs µH�m·@L"�W�y©c�7�¨�r£��?Å+M<����§´�g�²�?�U�y���z���W�?�1¬x§´�gÈĸ �`�k�W�L¡k�¤�� ON�P§RQg��±SLÄ���W�?¦L�Ê�¨�r£��?Ų°<¡k���������W¡b�g��¥E�b�`���?���¤ '¬x§´�gÈĸ��`�k�W�L¡k�¤�m Ni§RQg��±�¸

åyÏcî�ã/îfíZå�áÄÓiéÄçLåkçIä�áÄîLý�ä"åyáoçLå<å�áÄÓièfÓ�ôcîUêzÏcå�õ¼óoÓgôªéAîfíZå�áÄÓç�êzî�Ñoä�åyÏÉêIý³ç`è�ӴϪäãoÓ�çsÒyôÉõ(ÏÉã�òoáoçfä�ÓIýÊÏcå�á�å�áÄÓÇò9î�ä�Ïcå�ÏÉîfãîfívåyáÄÓ ü Ózå!ç�äÊêgçfã ÷ Ó´ä�Ó�Ógã�ÏÉã¢ó9ÐfÑÄÒyÓ��oì ÷ îså�åyîfæ�ÕÚÇÜ0TU�/Û¢ÝV�W�/ÙX������ Y�/ÙZ��Ú´Ø�ÜAÙ Ü![ Ú0\Z��HÞK����Û����]�HØ�ÜËÙ^�@[H[H��ß¼Úÿ¨ã óoÐfÑÄÒyÓO�×ç×ä�áÄÏríxå�îfí´å�áoÓÌèfÓgôÉîUêzÏcå�õ�ò9Ó?çsù çfãoé ç

ä�ôÉÏcÐ�á�åyôcõ'ÏÉãoêgÒ�Ó?çfä�Ó�é'ýÊϪé$å�á%Ϫä�î ÷ ä�ÓgÒyèfÓ?éZÕ�( æ7Ó�Ò�Ó7ä�áoÏríxåϪäiãÄîsåiôcÏÉùfÓ�ôcõ(åyî/òÄÒyîUéUÑoêzÓÇçAôªçsÒyÐfÓÇêkáoçsãÄÐ�Ó´ÏÉã'å�áÄÓÇáoçfÒ�öæ7î�ãÄÏÉê0êzî�ã�åyÓgã�å¢îfí�å�áÄÓ0èfî�ôcÑÄæ7Ó'â9îLý Ïcã�å�î�å�áÄÓ0âoÑUåyÓfÕà²áoÓ%è�îfÒ�å�Ó.1 ä�áÄÓ?éÄéUÏÉãÄÐ�Ógè�Ógã�å�ÑoçfôcôÉõ�áoçfä(åyî ÷ Ó%åyçfùfÓ�ãÏÉã�å�î7çfê�êzîfÑoã�å?Õ~à²áoÓiä�æËçsôÉô@ä�áÄÏcíxå³îfí�å�áoÓòÄá9çfä�Ó ÷ Ózå�ý³ÓgÓgãåyáÄÓ¯òCî�ä�Ïcå�ÏÉîfãIçfãoéiå�áÄÓ³çfêgîfÑoä�å�ϪêEèfÓ�ôcîUêzÏcå�õóoÓgôªé�Ïcã9éUÏÉê�çLåyÓ�äåyáoçLå~å�áoÓ ü Ózå~ÏÉävÓgè�Ógã�å�Ñ9çsôÉôcõ�éUÒyÏcè�Ógã´ÒkçLåyáÄÓgÒ ÷ õiå�áoÓ5å�Òkçsã9ä�öè�ÓgÒkä�Ó�âoîLý×å�áoçfã ÷ õÇåyáÄÓ�åyÒyçfãoä�è�ÓgÒkä�Ó³âoîLý ç�êgêzÓ�ôcÓ�Òyçså�ÏÉîfã�Õß7ÜAÙ�ßR <ÞV�HØ�ÜAÙà²áÄÓ²æ7îfÑUåyáIÒyÓ�ä�îfãoçfãoêzÓ5í¶îfÒ~âoÑUåyÓ³çfãoé´ÒyÓ�êgîfÒkéUÓgÒvòÄôÉç`õ�ö

Ó�Òyä�ÏÉä!æÇÓ�ã�å�ÏÉîfãÄÓ?é¢ÏÉã�ï Gsðvç�ä ÷ Ó�ÏcãoÐAÏcæ7òCîfÒ�åyçfã�åÊí¶î�Ò�òÄÒyîsöéÄÑoêzÏÉãÄÐ0ç'å�îfãoÓ¢ë�ÑoçsôÉÏcå�õ0ýÊáÄϪêká�Ϫä´ôÉÓ�äyäIä�áÄÒyÏcôÉômÕ�ÿ¨ãÌå�áÄϪäò9çsòCÓgÒAåyáÄÓ�ç�ä�ä�Ó�äyä�æ7Ó�ã�åAîfí´çsã Ó-@Ó�êzå¢ÏªäËæËçféUÓ�ýÊáÄÏÉêkáä�ÑÄòÄòoÒ�Ó?ä�ä�Ó�ä�å�áÄÓ5Ó�èfÓ�ã�áoçsÒyæ7îfãÄϪêgävçLåvçÊòoÒ�î�ò9Ó�Ò�ôÉõä�áoçsòCÓ�éè�îUêgçsôvå�Òkçfêzå�Õ�à²áÄÓ¼óoãoéUÏÉãÄТîsí<ç/òÄáoçfä�ÓÇæÇîUéUÑoôÉçså�ÏÉîfã�îfíåyáÄÓÇèfÓgôÉîUêzÏcå�õ¢òCÓ�çfù'çLå!åyáÄÓIæ7î�ÑUå�á0Ò�Ó?ä�î�ãoçsãoêgÓ�æËç`õ¢ÏÉãUöéÄÏÉê�çLå�Ó´çfã¢Ó.1UòÄôÉçfãoçLåyÏcî�ã�ÕÛ��@[H�iÛ��iÙ�ß����_7`bac`"d&e5f"gih)e5j�k%lY`"m]nogqpirts.f&h:giu�v�wyx{z7|t}�~t�7���R���.��� }B�{�@�q���y� ���

� � |i�����"���S� ��|:�+�I���S�S}������i�0���{�c�{�t���R����S� |�l]���F�c .¡¢�£ ��l+¤¦¥7§�` ¨7©"v&ª7«7«¬¡­©"_�®%¯�°7®7®7®±

°"`b²�`´³µ`¶�y¥7§ ·i¸¹e5j�v��0��{��x!�º��|��7�&��&~i�R��»]�t~���|H}�����x"�½¼y�"�¾��¿²7l) {l+¤¶¥7§�` ª5À�v"À�_SÁ%¯º_�«Á5±

Â"`bac`.d&e5f�gih]h:·�e5§�`ov¦Ã'�7���¾��Ä�|qx"�t��7}B�{�¹}B��|t�¾�i�.�7zH�7|�~�}��B� �7��}��7���q���¼y���)�7���.�7�<�&} �{��l]� ¢ l�l]���F�c  ¢�£ �yl�¤¦¥7§�`.¨7°"v"¨7©7¬¡¾¨Á7Á¯q_�«Á5±

À�`ÆÅY`{ {rts�h:rtÇ&v ÈÉ}����¶�tÊ����:¿�˶k"n ·ino¥7j¹ac`. .rts�¥5·º·SÌ p� 'Í¥7s"j�h7v"Î�e5noj"Ï_�«Á5ª

Embouchures and end effects in air-jet instruments.

Joe Wolfe and John Smith

School of Physics, University of New South Wales, Sydney NSW 2052, Australia, J.Wolfe@unsw.edu.au

In the flute family of instruments, the control oscillator is an air jet, which acts at an end of the bore that is open to theatmosphere. The air jet thus experiences a radiation impedance determined by the size of the aperture at the jet and thesolid angle it subtends. These are varied by the player's embouchure, the upper lip and face. To adjust the intonation,players of the transverse flute rotate the instrument about its long axis, thereby partly covering the hole, varying theradiation impedance and changing the end effect. In the end-blown shakuhachi, players move the flute and the head inthe vertical plane to achieve even greater changes in the end effect and pitch. We report measurements of the radiationimpedance of the playerÕs embouchure as 'seen' by the instrument Ôlooking outÕ. Independently, we measured theacoustical impedance of the instrument itself, measured at the position of the jet, but 'looking into' the instrument.Adding these gives the total effective impedance of the instrument in the playing configuration. Changes in thisimpedance with different embouchure can account for most or all of the observed changes in pitch, and may alsocontribute to changes in timbre.

INTRODUCTION

The air-jet family of instruments includes side blownflutes such as the Western flute, and end-blown flutessuch as organ pipes, recorders and the Japaneseshakuhachi, which is gaining renown because of itspopularity in 'world music'. Because they are excitedby an oscillating air jet, they are open to theatmosphere at the point of excitation. The jet is thusloaded by the acoustic impedance of the bore and thatof the radiation field at the hole left open at the jet. Asimilar situation in the organ pipe has been analysedby Fletcher and Rossing [1], who conclude that theeffective impedance acting on the jet is that of thebore in series with the radiation impedance. The radiation impedance or end effect can be variedby varying the size of the hole at the jet, the solidangle available for radiation, or both. In the transverseflute, this is achieved by rotation of the instrument sothat the player's lower lip occludes more or less of theembouchure hole, and the upper lip and the rest of theface baffle more or less of the solid angle. Flutists usethis technique to play in tune under varyingconditions of loudness and required pitch adjustment. In the shakuhachi, the player's chin closes the endof a nearly cylindrical pipe (Fig 1). A chamferprovides both the edge (which usually includes aninsert of a hard material) and the embouchure hole.Players vary the position of the chin, the angle of theinstrument and the angle of the head to effect largechanges in the area and angle available for radiation.This gives the instrument a great flexibility in pitchand timbre, which have become importantcomponents of both traditional and contemporaryplaying styles. With organ pipes, fine tuning adjustments are made

by changing the shape of 'ears' on either side of thejet, which varies the solid angle for radiation, butrecorders do not use this technique. We report here theresults for the shakuhachi and transverse flute.

FIGURE 1. The shakuhachi and player Riley Lee.

MATERIALS AND METHODS

The impedance spectra of flutes and shakuhachis,without players, were measured as describedpreviously [2,3], except for the treatment of theradiation load at the embouchure. To measure theimpedance of the end effects, the impedance head wasplaced inside the embouchure end of a flute or ashakuhachi, so that it measured the impedance of theexternal field in series with a small section of knowngeometry. The field impedance was calculated usingthe transfer matrix. The players were distinguished concert andrecording artists. They were asked to mime the

embouchures required for normal playing, and forplaying to produce notes with different intonations.This procedure is highly reproducible: it is what anexperienced musician must usually do just beforebeginning to play if s/he is to play in tune.

RESULTS AND DISCUSSION

FIGURE 2. The impedance 'seen' by the shakuhachi.

Figure 2 shows the impedance of the shakuhachiplayer's embouchure as used to play the notes ro andro meri. Both are played with all finger holes closed,but the former has the normal pitch and the latter is asemitone lower. Note that the impedance increasesroughly at 6 dB/octave, but that the meri embouchurehas a higher impedance. The resonances of the player'svocal tract are visible as small features (at around 2.4and 3 kHz in the meri curve, higher in the normalcurve). Although the resonances of the tract may bestrong, the narrow aperture between the player's lips isonly a small fraction of the solid angle for radiation.In measurements on a beginning player (one of theinvestigators) the vocal tract resonances are muchmore visible. The scatter at low frequency is due tobackground noise. This was smoothed over ±10 Hzfor the calculations yielding the figures below. The sum of the instrument and embouchureimpedances are shown in figure 3: the upper figureshows the normal embouchure and the lower the meriembouchure. (Measurements of impedance for theshakuhachi alone were made previously [4].) The frequencies of the minima are lower in the mericase by 140, 100 and 65 cents, and are also lessharmonic than those of the normal embouchure. Thisis sufficient to account for the observed difference (1.0semitone flat) produced in a played note. The meriresult also shows shallower impedance minima athigh frequencies. Along with the decreasedharmonicity, these may be in part responsible for thedarker timbre of the meri notes. Similar results are obtained for the transverse flute.These are reported in greater detail elsewhere [5]. Weconclude that, although the jet speed and otherparameters may be adjusted, the end effect is

sufficient to account to first order for the observedtuning effect.

FIGURE 3. Impedance of a shakuhachi plus theradiation load measured at the embouchure.

ACKNOWLEDGMENTS

We thank Riley Lee, Geoffrey Collins, Tom Deaver,John Tann and the Australian Research Council.

REFERENCES

1. N.H. Fletcher and T.D. Rossing, The Physics of MusicalInstruments. New York, Springer-Verlag, 1998.

2. J. Wolfe, J. Smith, J. Tann, and N.H. Fletcher, J. Sound &Vibration, 243, 127-144 (2001).

3. J. Wolfe and J. Smith, "Acoustics of the air-jet family ofinstruments", in Proc. 7th Western Pacific Regional AcousticsConf. Kumamoto, Japan, pp 575-800, 2000.

4. Y.Ando and Y.Ohyagi. J. Acoust. Soc. Jpn. 6 , pp 89-101(1985).

5. J. Wolfe, J. Smith and J. Tann. "Flute acoustics"www.phys.unsw.edu.au/music/flute.

Experiments on mouth-tones during transients and steady-state oscillations in a flue organ pipe

Fabre B.,Castellengo M.

Laboratoire d’Acoustique Musicale, Univ. Paris 6, 4 place Jussieu, 75252 Paris Cedex 05, FRANCE

Attack transients are known to be very important for the perception of the tone quality of flue organ pipes. This may be related to the complexity of the physical phenomena that can take place during the transient. This complexity turns the physical understanding and modeling to a challenge. Experimental investigation of the attack transient shows phenomena that can be related to an edge-tone oscillation or to a pipe-tone oscillation. Oscillating frequencies in an edge-tone geometrical configuration are compared to those obtained in an organ pipe configuration. Measurements show that the edge-tone like oscillation that can take place at some stage during the attack transient can also appear during steady-state oscillations above the oscillation threshold.

INTRODUCTION

Attack transients in musical sounds are known to be very important for perception. Recent work by Rioux [1] shown that, in the case of flue organ pipes, the attack transient plays a major role in the subjective tone quality. Furthermore, the organ builder gives special attention to the attack transient during the final adjustment of the pipe geometry known as “voicing”. The physics involved during transients is complex since it mixes unsteady flow dynamics with acoustics. If some aspects of organ pipe physics are well enough understood to allow the present models to predict steady-state oscillation in the pipe as far as order of magnitudes are concerned, it is definitely not the case for attack transients. The purpose of this paper is to present experimental data that show the different phenomena that can be observed during the attack transient and to discuss how those phenomena can be accounted for by the present models.

EXPERIMENTS

Experimental setup

Experiments were carried on a metal ogan pipe with circular cross section of 27mm diameter and 312mm length. The flue exit-labium distance is 7mm and the flue height is 0.20<h<0.30mm. The mouth is 21mm wide. It offers the possibility to separate the pipe from the mouth, allowing us to compare an edge-tone configuration and the pipe configuration while keeping the same mouth geometry.

Time stages of the attack transient

As previously discussed by Fabre [2] and Verge [3], the attack transient can be separated in four time stages.

Stage 1 is the very beginning of the transient. The foot pressure rise is pushing an initial flow from the flue towards the labium acting as a volume injection and giving rise to the initial acoustic pulse that triggers the whole transient as shown by Verge [3]. From experimental results, theoritical investigations and flow simulations, it appears that the duration of stage 1 lies between 0,5T and 3T where T is the inverse of the frequency of the first pipe resonance.

Stage 2 starts when the flow reaches the labium. The complex interaction with the labium acts as a source on the fluid, and may act on the jet itself. An oscillation often takes place which may induce an acoustic resonance (longitudinal and/or transversal resonance of the pipe). The oscillation may as well not induce any acoustic resonance, but instead, rely upon the direct action of the source on the jet like that observed in the case of an edge-tone. Experimental works [2,5] indicate that oscillations during stage 2 appear at frequencies much higher than the fundamental of the future steady-state. Flow visualization [3] indicate that the flow behaviour may be very complex at that time. During stage 2, the threshold for auto-oscillation is not reached but the pipe starts to accumulate acoustic energy at the longitudinal resonance frequencies of the pipe. Stage 2 ends when the jet velocity as well as the acoustic energy stored reach the auto-oscillation threshold: at this point, the higher frequencies that appeared during stage 2 disappear.

During stage 3, the system has reached the

oscillation threshold : the jet velocity as well as the

acoustic energy already stored in the pipe are high

enough to maintain auto-oscillation. The jet

mouvement is locked on one of the longitudinal modes

of the pipe. The transverse jet mouvement is large and

the source associated with the jet oscillation is

probably at saturation. The pipe accumulates energy at

that frequency so that the acoustic oscillation in the

pipe is growing for a time depending on the quality

factor Qn of the nth pipe resonance[2] : t3~Qnfn.

Stage 4 is the saturation of the acoustic oscillation in

the pipe, which appears [4] to be related to vortex

shedding induced by the acoustic field. During stage 4,

the oscillation regime of the pipe may change from a

higher to a lower longitudinal mode of the pipe. If this

does not occur, stage 4 is very short.

Under normal blowing conditions, the global

duration of the attack transient is dominated by the

duration of stage 3. However, for some organ pipe

ranks like the italian “viola” [5], the special voicing of

the pipe allows to stabilize the oscillation at stage 2

when mouth-tones and pipe-tones can exist together.

Apart from this very special voicing, stage 2 may still

be the most important as far as perception is concerned

since it induces an oscillation at a frequency much

higher than the steady state oscillation.

Mouth-tones

Experimental investigation of the attack transient by

Castellengo [5] showed the existence of mouth-tones

with edge-tone like frequency behaviour. These mouth

tones appear at stage 2 : indeed, several oscillating

regimes can co-exist at that time since the system has

not reached its saturation. Comparison of the sound

produced by the complete pipe and by the mouth only

(edge-tone) configuration indicates that the mouth-

tone is reinforced when its frequency matches one of

Fig 1 Time-Frequency analysis of the attack transient

on the edge-tone configuration (left) and on the organ

pipe configuration (right)

the pipe resonances. Despite this possible frequency

matching, the systems seems not to be locked on one

of the pipe modes : its frequency appears to still evolve

independantly of the pipe resonance as seen on figure

1.

DISCUSSION

Two different loops are generally considered in

lumped model description of flue organ pipes [4]. The

first loop uses a direct hydrodynamic feedback of the

source at the labium on the jet. The second one goes

through the pipe resonance. Verge [3] has shown that

the second one is dominant during steady-state

operation. The first seems to be dominant during stage

2 while the system is operated below its oscillation

threshold.

Following Coltman’s experiment, we carried

frequency measurements (fig. 2) on both geometrical

configurations (with and without pipe) as function of

the jet velocity. It appears that mouth-tone steady-state

oscillations can exist below the pipe-tone threshold.

These are characterized by their very low radiation and

their great frequency sensitivity to blowing pressure

fluctuations. Further measurements on the oscillation

amplitude should be carried.

Fig 2 : Steady-state oscillating frequencies on edge-

tone system for the first three modes (∆, ,+) and on

the complete pipe ( ).

REFERENCES

1.Rioux V, Acta Acustica, 86(4) (2000), 634-641.

2.Fabre.B & al, Journal de Physique., Colloque C1 (1992)

67-70

3.Verge M.P. & al., J. Acoust. Soc. Amer., 95(2) (1994)

1119-1132.

4.Fabre B. & al, Acta Acustica 86(4) (2000), 599-610

5.Castellengo M., Acta Acustica, 85(3) (1999),387-400

6.Coltman J., J. Acoust. Soc. Amer., 60 (1976), 725-733

Spontaneous and Induced Spanwise Variability in Self-Excited Air Jet Oscillation

A. Wilson Nolle

The University of Texas at Austin, Austin, Texas 78712 USA

At low Reynolds numbers, a self-excited oscillating planar jet (the edgetone system) approximates two-dimensional flow.Breakdown of edgetone two-dimensionality occurs in ranges of flow velocity where competition between oscillatory modescauses intermittent loss of amplitude, which is not simultaneous along the span. Forced breaking of two-dimensional edgetonesymmetry is produced by inclining the edge,. the standoff distance varying linearly along the span. Hot-wire signals at the centerof the span contain a spectral triplet. The outer two lines are the main components in the acoustic radiation. Their frequenciesclosely match those in separate edgetone experiments with the edge parallel to the flue and with standoff distance matching oneend or the other of the inclined edge. The hot-wire spectrum at an end of the inclined edge is dominated by just one of thesefrequencies. The effect of the inclined edge in organ-pipe oscillation, where the edgetone can produce anharmonic partials, isinvestigated. Examples are found where the anharmonic partials diminish or vanish when the inclined edge is used.

EXAMPLES OF SPANWISE FLOW VARIATION IN EDGETONE

The spontaneous oscillation of a planar jet striking an edgecan be regarded as a two-dimensional phenomenon for manypurposes. However, flow dependence on the third (spanwise)dimension can occur, for example, (1) when the jet hasevolved toward chaos; (2) when competing modes ofoscillation interfere intermittently; and (3) when theedge is not made perpendicular to the stream direction.This paper will show examples of (2) and (3), and thenreport some consequences of (3) in organ pipeoscillation. Reynolds numbers are about 500 to 1500. All results are obtained with a parabolic flow from a 1mm wide channel flue, streamwise length 25 mm, span38 mm, except that an organ-style jet with sharplanguid will be considered in the final example. Theedge or lip struck by the jet is of square-cut sheetmetal, thickness 1.6 mm.

50403020100time,millisec

FIGURE 1. Flow in an edgetone apparatus, recorded sim-ultaneously by two probes near the edge, 4.5 mm apart..Rectangles mark interference epiusodes. Velocity 8.4 m/s.Flue to edge distance, 8 mm.

Figure 1 shows an example of intermittentinterference episodes.. These do not occur simul-

taneously at the two probes, indicating that the flowvaries along the span. Two modes of oscillation, offrequency ratio about 2.95, are involved. If the samestream velocity is approached slowly from smallervalues, only the lower mode at 390 Hz is present andthe probes show similar periodic waveforms.

2000

1500

1000

500

0

Horizontal edge

2000

1500

1000

500

0

500040003000200010000freq., Hz

Slanting edge

FIGURE 2. Top, velocity spectrum for horizontal edge;bottom, for slanted edge.

Figure 2 illustrates the effect of forced spanwisedependence of the flow. The upper graph shows thevelocity spectrum near the edge for a uniform standoffof 8 mm (flow velocity 16 m/s). When the edge isinclined so that the standoff varies from 7 to 9 mmalong the span, the spectrum in the lower graph isfound. Single lines are each replaced by two strong,well separated components, with a weaker componentbetween. Further work shows that the component of

highest frequency is dominant at the low end of theedge, and vice versa.

RELATION TO ORGAN-PIPEOSCILLATION

Edgetone frequencies can occur as anharmonic com-ponents in organ-pipe oscillation [1]. Modulation ofsuch components appears to contribute to a buzzing orfrying sound [2] that is sometimes considered ob-jectionable. The preceding excperiments, showingmodification of the edgetone by inclination of the edge,suggest that a slanted lip can modify the edgetone-produced anharmonic components in organ-pipeoscillation. Two examples follow. Acoustic spectra in Fig. 3 are from a laboratory organpipe using a horizontal upper lip, and one using aninclined upper lip (cutup varying from 7 to 9 mm).With the horizontal lip there is a component, alsofound in edgetone measurements, at 5.25 times the 306Hz fundamental. With the slanted lip these componentsdisappear (but also amplitude of the second harmonicin the pipe oscilllation decreases).

1.0

0.8

0.6

0.4

0.2

0.0

1086420Frequency relative to fundamental

Horizontal lip (microphone)

1.0

0.8

0.6

0.4

0.2

0.0

1086420Frequency relative to fundamental

Slanted lip(microphone)

FIGURE 3. Organ-pipe simulation, 300 Hz. Open resonator,38 mm square by 473 mm long. Acoustic spectra with hori-zontal and with slanted lip. 18.3 m/s central flue velocity.

In the final example the flue was the passagebetween the front pipe wall and a languid, as usual inorgan principal pipes. This languid is a machined part,with a sharp edge. Chaotic content in the jet flow wasmuch greater than before, and voicing adjustments lesscritical. Anharmonic behavior was difficult to find, butwas obtained (Fig. 4) with the resonator lengthened. In

this case, using the inclined edge makes a modestreduction in the anharmonic component at 4.1 timesthe fundamental frequency, but does not remove it.

0.30

0.20

0.10

0.00

876543210Frequency relative to fundamental

With horizontal lip

5.04.54.0

5.04.54.0

Slanted lip

FIGURE 4. Top: Acoustic spectrum of pipe having fluewith languid. Passage width 0.29 mm. Ears, projecting 12mm, fitted to mouth. Resonator length 661 mm. Fluevelocity 15 m/s. Fundamental frequency, 236 Hz. Lower left:Detail from upper graph. Lower right: Comparable detail forinclined lip (7 to 9 mm), showing reduction of anharmoniccomponent.

While anharmonic content can sometimes be reducedby inclination of the lip, it appears that the level ofturbulence at the lip can be more important. Also,anharmonic behavior is sensitive to pipe scale and tovoicing details.

REFERENCES

1. Castellengo, M., Acustica-Acta Acustica 85, 387- 400 (1999). 2. Monette, L. G., The Art of Organ Voicing, New Issues Press, Kalamazoo, Michigan, USA, 1999, pp. 73-74.

Experimental Study of the Velocity Field at the SideHolesandTermination of a Tube

D. Rockliffa, J.-P. Dalmontb, D.M. Campbella

aTheUniversityof Edinburgh,UKbLaboratoired’Acoustiquedel’Universite duMaine(UMRCNRS6613),France

The velocity field close to tone holes on a woodwind instrument has a significant effect on the behaviour of the instrument. Thisis particularly noticeable in the lowest register of an instrument, where acoustical streaming velocities can be quite prominent.Previous investigations have developed theoretical models to describe the acoustical behaviour of side ducts [1], which have beensupported by experimental measurements. The non-linear behaviour of tube terminations of varying shapes has also been investigatedexperimentally and theoretically [2, 3].This work presents an experimental investigation of the non-linear behaviour at the termination of a tube. Firstly, a purely acousticmeasurement of the non-linear radiation impedance is taken. Secondly, Particle Image Velocimetry (PIV) is used to obtaininstantaneous full-field maps of the acoustic particle and streaming velocities at the tube termination. The acoustic measurement ofthe radiation impedance shows a non-linear resistance proportional to the volume velocity at the end of the tube whose value is foundfrom the PIV velocity maps.

INTRODUCTION

The acoustic field in the region of a tube terminationhas been investigated by many authors. Understandinghow the velocity field interacts with the walls at tubeopenings is particularly relevant in the study of wood-wind instruments, where the behaviour of the acousticfield in the vicinity of the tone holes can significantly in-fluence the sound produced by the instrument. In addi-tion, the sound intensity found just inside the tone holesof a woodwind instrument under playing conditions canbe very high, leading to non-linear effects such as vor-tex shedding. The acoustic flow in the exit of open-endedpipes at resonant frequencies has been previously investi-gated [3]. Theoretical models developed by Dubos et al.[1] to describe the acoustical behaviour of side ducts havebeen supported by experimental measurements.

The aim of this paper is to examine the non-linear be-haviour at the open end of a cylindrical tube and in ashort side duct at sound pressure levels comparable tothose found on real woodwind instruments under play-ing conditions. Acoustic streaming and particle veloci-ties are investigated using PIV, and the results are com-pared to acoustic measurements of the non-linear radia-tion impedance using conventional techniques.

Non-linear behaviour at a tube termination

Experimental investigations by Ingard and Ising [2]showed that the radiation impedance at an orifice is lin-ear for low acoustic field intensities, but develops a non-

linear resistive term proportional to the velocity ampli-tude at high intensities. Experiments in the exit of openpipes at acoustic resonance [3] showed that the coefficientof proportionality of the resistive term may be affectedby the edge sharpness of the tube termination. Recently,an experimental investigation of linear and non-linear be-haviour at side holes has been carried out by Dalmontet al. [4]. A tube with upper end open and a side holewith relative dimensions corresponding to that of a wood-wind instrument was constructed. The tube was excitedat frequencies around the first resonance of the tube by acompression driver excited by a sine wave, and radiationimpedance measurements were taken at the side hole andmain tube termination for both small and large amplitudesound fields. The dimensions of the side holes and degreeof edge sharpness was also varied. At low amplitudes,

FIGURE 1. Real part of the non linear part of the shuntimpedance as a function of acoustic Mach number Mh for a sidehole of radius 7mm (taken from [4]).

FIGURE 2. A photographic image of the acoustic flow at theopen end of tube being excited at a resonance frequency of 985Hz and sound field intensity of 133.5 dB (re 20µPa).

the measurements agreed well with theoretical results[1, 5]. For large amplitude sound fields, the radiationimpedance showed a non-linear part proportional to thevelocity in the side hole, as reported in [2]. This wasfound to depend on the inner edge sharpness of the hole.A graph of the non-linear part of the shunt impedance asa function of acoustic Mach number is shown in Figure 1.

The measurementof non-linear behaviourin acousticsoundfieldsusingPIV

Particle Image Velocimetry (PIV) is a non-intrusiveoptical technique which allows the simultaneous mea-surement of flow velocities at many points in a two-dimensional plane. In a typical experimental set-up,tracer particles suspended in a fluid are illuminated twicein a short time interval by a thin light sheet projectedthrough the flow. Light scattered by the particles isrecorded on two separate frames by a digital cameraplaced perpendicular to the flow. By determining the par-ticle displacement between frames and knowing the timeseparation, the fluid velocity motion can be calculated.

The aim of the work is to investigate the flow field neartube terminations under conditions comparable to thosefound for a woodwind instrument under normal playingconditions. Sound pressure intensities exceeding 160 dBwere recorded just inside the exit of a side hole on a clar-inet when played fortissimo. Hence, acoustic particle andstreaming velocities are measured at frequencies aroundthe first resonance of the tube i.e. 200-600 Hz for soundfield intensities up to and above 160 dB. Once the vectormaps have been obtained, further analysis is completedto quantify the radiation impedance and hence the ampli-tude of the non-linear term.

FIGURE 3. Acoustic particle velocity map corresponding toFigure 2.

Resultsand Discussion

A photographic image of the instantaneous acousticparticle velocity field taken at the end of a tube when ex-cited at a resonance frequency is shown in Figure 2. Thecorresponding velocity map at the point in the acousticcycle where the particles are travelling into the tube canbe seen in Figure 3. It is clear from this figure that partsof the image did not yield velocity measurements, partic-ularly adjacent to the tube walls, due to flare. Althoughthis is unavoidable when working with cylindrical tubes,it does not affect observations of particle displacementson the central axis of the tube or in the region around theexit of the tube, which are important in the observationand measurement of non-linear behaviour of the acousticfield at this point. Experimental work is currently beingundertaken, and results will be presented at the confer-ence.

ACKNOWLEDGMENTS

The financial support of EPSRC is gratefully acknowl-edged. We thank J.-P. Dalmont for discussions on acous-tic fields at tube terminations.

REFERENCES

1. V.Dubos, D.Keefe, J.Kergomard, J.-P.Dalmont, A.Khettabiand C.J.Nederveen , Acustica, 85, 153-169 (1999).

2. U. Ingard and H. Ising, J. Acoust. Soc. Am. 42, 6-17 (1967)

3. J.H.M.Disselhorst and L.Van Wijngaarden, J. Fluid. Mech.99(2), 293-319 (1980).

4. J.-P. Dalmont, C.J. Nederveen, V.Dubos, S. Ollivier, V.Meserette and E.te Sligte, accepted for publication in Acus-tica.

5. C.J.Nederveen, J.K.M.Jansen and R.R.van Hassel, Acus-tica, 84, 957-966 (1998).

Time-domain Simulation of Sound Production of the ShoT. Hikichi and N. Osaka

NTT Communication Science Laboratories3-1, Morinosato Wakamiya, Atsugi, Kanagawa 243-0198, Japan

This paper proposes a physical model of the sho, one of the Japanese traditional musical instruments, with intention of applyingthe model to sound synthesis. A time-domain simulation clarified the effects of the tube length and blowing pressure on the soundfrequency and other attributes. To confirm the model, reed vibration and the pressure variation inside the tube were also measured byartificially blowing the sho. The agreement between the experimental results and simulation is acceptably good for the relationshipsbetween the tube length and threshold pressure, and between the tube length and the sounding frequency.

INTRODUCTION

The sho is a free-reed mouth organ that is used in tradi-tional Japanese court music called “Gagaku.” It is mainlycomposed of a mouthpiece, cavity, and seventeen bamboopipes. Bronze reeds are glued with resin to the lower sideof the bamboo pipes. When a player blows in throughthe mouthpiece and closes the small finger holes on thetubes, oscillation commences and the reeds start sound-ing. Some tubes have one slot besides the finger hole,which determine the effective lengths. It is categorized asa free-reed instrument like the harmonica, accordion, andreed-pipe organ. However, unlike the other Western freereed instruments, the reeds of the sho are approximatelysymmetrical, so that the same reed vibrates on both blow-ing and drawing.

The instrument is said to originate in the 3rd or 4thcentury in China, and there are other musical instrumentsthat work on a similar mechanism: the Chinese sheng,the Laotian khaen and others, mostly found in easternand southern Asia. For khaen, Cottingham has examinedits acoustical properties and reported that sounding fre-quency decreased with increasing blowing pressure, andthat the frequency changed with changing tube length [1].The main difference between the sho and the khaen liesin the position of the reed. In the sho, the reed is locatedat the one end of the pipe, whereas in the khaen the reedis at a position L/4 from the end.

This paper proposes a physical model of the sho, andpresents results of a time-domain simulation that was car-ried out to investigate effects of the tube length and blow-ing pressure on the sound frequency and sounds spectra.To model the reed vibration and flow through the reed,we adapt the formulation used in the reference [2].

PHYSICAL MODEL

The physical model of the sho is briefly described.Here, only one tube is considered for simplicity, but

FIGURE 1. Overview of the sho, the Japanese free-reed mouthorgan.

extension is easy. We focus on the “Ichi” tube (B4,482.7Hz), because this tube does not have any slot on theside wall, therefore it can be regarded as a cylinder.

Assume pressure at the upstream of the reed (i.e., pres-sure inside the cavity) p(t), pressure at the downstream(pressure inside the pipe) p2(t). When the reed is as-sumed to vibrate at the normal mode, the equation of mo-tion of the reed is

d2xdt2 +

ωr

Qdxdt

+ ω2r (x− x0) =

1.5WLm

(p(t)− p2(t)), (1)

where x is the displacement at the tip of the reed, Q theresonance Q value, ωr the angular frequency, and x0 theinitial displacement. W , L, and m are the width, length,and mass of the reed, respectively. The derivation of Eq.(1) is shown in the Appendix in the reference [2].

From Bernoulli’s equation, the relationships amongp(t), p2(t), and volume velocity through the slit U(t) areas follows:

p(t) = p2(t)+ρ2

[U(t)

CF(x)

]2

+∂∂t

[ρU(t)δCF(x)

], (2)

where C is the flow contraction coefficient, which repre-sents the effect of the slit configuration. The area of theslit F(x) is described by

F(x) = W [x2 + b2]12 + 2L[a(x)2 + b2]

12 ,

where a(x) is the average displacement of the sides of thereed, and b is the gap width. For a sho reed, we assumex0 = 0. Considering it displaces both ways, and from theform of the mode function, a(x) = 0.4|x| is derived.

Since the pipe shape is approximated as a cylinder, weuse a simple reflection function of Gaussian type of theform

r(t) ={ −aexp{−b(t − τ)2}, t ≥ 0

0, t < 0

and adapt Schumacher’s method to calculate the pressureat the entrance of the pipe [3]. Using this reflection func-tion, we calculated the pressure inside the tube p2(t) as

p2(t) = Z0Uin(t)+ r(t)∗ (p2(t)+ Z0Uin(t)), (3)

Uin(t) = U(t)+ 0.4WLdx/dt ,

where Uin(t) is the net volume velocity input to the tube.Differential eqs. (1)∼(3) were discretized, and a sim-

ulation was done in 48-kHz sampling. Given p(t), thefollowing three variables were calculated: displacementof the reed x(t), pressure inside the tube p2(t), and vol-ume velocity U(t).

SIMULATION AND EXPERIMENTALRESULTS

Basic acoustical properties were examined both bysimulation and experiment. The properties that were ex-amined were:

• pipe resonance frequency fp vs. threshold behavior,• pipe frequency fp vs. sounding frequency fs,• blowing pressure vs. sounding frequency fs.

Because of the lack of space, only one example isshown here. Fig. 2 shows the measured and Fig. 3 thesimulated sounding frequency fs as a function of the pipefrequency fp. The pitch fs shows strong dependency onfp, and the results show similar tendencies. Oscillationcommenced only when fp < fs and fr < fs hold, wherefr is the reed resonance frequency. A more detailed dis-cussion will be presented in [4].

SUMMARY

A time-domain simulation was done to examine ef-fects of the tube length and blowing pressure on soundattributes. Simulation and experimental results show thatthe model reproduces basic characteristics which wereobserved in the actual instrument. Recorded and sim-ulated sounds have a common feature in the sense that

high frequency components of their spectra increase withincreasing blowing pressure. Further, from the frequencyrelationships among fp, fs, and fr, it was concluded thatthe reeds of the sho act as “outward-striking valves.”

ACKNOWLEDGMENTS

This research was supported in part by the Centerfor Integrated Acoustic Information Research (CIAIR),Nagoya University. One of the authors (T. H.) is gratefulto Professor F. Itakura, who is leading the center, for hisvaluable suggestions.

REFERENCES

1. Cottingham, J.P., Fetzer, C.A., Proc. of the ISMA, Leaven-worth, 1998, pp.261-266.

2. Tarnopolsky, A.Z., Fletcher, N.H., and Lai, J.C.S., J.Acoust. Soc. Amer., 108(1), 400-406 (2000).

3. Schumacher, R.T., Acustica, 48(2), 71-85 (1981).

4. Hikichi, T., and Osaka, N., Proc. of the ISMA, Perugia,2001.

100 200 300 400 500 600300

350

400

450

500

550

600

650

700

Pipe resonance frequency fp [Hz]

Soun

ding

fre

quen

cy f

s [H

z]

blowdraw

FIGURE 2. Experimental result of the sounding frequency asa function of tube resonance frequency fp (’blow’: positive,’draw’: negative pressures).

100 200 300 400 500 600300

350

400

450

500

550

600

650

700

Pipe resonance frequency fp [Hz]

Soun

ding

fre

quen

cy f

s [H

z]

simulation (Q=30) simulation (Q=400)

FIGURE 3. Simulation result of the sounding frequency.

Investigation of Perceptual and Articulatory Correlatesof Tonal Ideals in German and Italian Schools of

Classical Singing

K. Verdolinia, B. Storyb, and M. Taylorc

aCommunication Sciences and Disorders, School of Health and Rehabilitation Sciences, University ofPittsburgh, 4033 Forbes Tower, Pittsburgh, Pennsylvania 15260 USA ( kittie@csd.pitt.edu)

bDepartment of Speech and Hearing Sciences, University of Arizona, P.O. Box 210071, Tuscon, Arizona86721 USA (bstory@u.arizona.edu)

c245 Atkins Avenue, Lancaster, Pennsylvania 17603USA (margarettahanna@aol.com)

We examined perceptual and articulatory correlates of tonal ideals in German versus Italian approaches to classicalsinging. Sung phrases were synthesized on /a/. Labial, oral, and pharyngeal areas were successively varied relative toa neutral mode, holding glottal source constant. Phrases were rated perceptually by expert, uninformed judges.Primary results were: (1) Both German and Italian ideals were most frequently described perceptually as “front,”“open,” and “bright;” (2) phrases identified as Germanic tended to be produced with a relatively larger pharynx andnarrower lips, as compared to Italian phrases, which were most often associated with a slight-moderately open vocaltract.

According to one or more prominentapproaches to vocal pedagogy, anecdotally, theGermanic tonal ideal in classical singing isperceptually “back,” “open,” and “dark” (or“covered”). In comparison, the Italian ideal ismore characteristically “front,” “closed,” and“bright” [1]. Various articulatory gestures canbe conceived—and have been proposed—asphysiologically causal to the respectiveperceptual targets [1]. The purposes of thepresent study were (a) to provide experimentaldata about salient perceptual attributes ofGerman versus Italian tonal ideals in classicalsinging, and (b) to provide quantitativeinformation about possible articulatorycontributions to the perceptual ideals [2].

METHODS

A series of sung phrases was synthesized usingan approach based on exciting a tubularrepresentation of the vocal tract (in the form ofan area function) with a voice source waveform.The voice source waveform was generated with aparameterized glottal flow model [3]. A digitalwaveguide was used to simulate acoustic wavepropagation in the vocal tract (energy losses dueto yielding walls, viscosity, and acousticradiation were included). The particularimplementation as used in this study is calledSpeechMaker [4]. A glottal flow waveform, used for allconditions in the experiment, was created for a

standard sung phrase from “The Heavens areTelling” by interpolating the fundamentalfrequency parameter through the musical notesof the phrase, on /a/. All other source parameterswere held constant. The vocal tract shape was represented as a 44-section area function. Sections (areas) 1-9 wereconsidered to be the epilarynx, 10-22 pharynx,23-39 oral cavity, and 40-44 lips. Each sectionassumes a length of 0.396 cm, producing a totalvocal tract length of 17.42 cm (44 x 0.396). Thebaseline (neutral) area function was for an adultmale vowel /a/, based on Magnetic ResonanceImaging data by Story [5] (Figure 1). For thepresent study, this area function was manipulatedby independently varying the areas ofpharyngeal, oral, and lip regions 100%,75%,50%,25%,-25%, -50%, and –75% relativeto the neutral configuration, while holding theremaining regions neutral. A total of 3 (regions)x 7 (area manipulations) phrases were created forpresentation to judges. Synthesized phrases were played to 4 expertjudges, 1 female and 3 males, ages 39-59 yr, allwith normal hearing bilaterally at 20 dB HL to8000 Hz, who had taught classical singing for17-20 yr. All judges indicated familiarity withGerman and Italian tonal ideals. Judges wereasked to use their own internal criteria to indicatethe degree to which each phrase conformed tothe German and to the Italian ideal (poor,medium, or good conformation). For eachphrase, judges further indicated, forced choice,

Figure1. Baseline (neutral) vocal tract.

whether the sound was dark or bright, closed oropen, and back versus front. Each phrase waspresented independently to each judge 3 times, inrandom (and different) orders across judges.Rating sheets were varied to control for possibleright/left response biases. A neutral aural“calibration” phrase was presented prior to thestart of each rating session, and after each set offive phrases, as a perceptual anchor.

RESULTS AND DISCUSSION

Perceptual data indicated that the mostcommon perceptual attributes for tokens judgedas medium or good exemplars of both Germanand Italian sounds were “front,” “open,” and“bright” (data not shown). This finding partiallycontrasts with anecdotal descriptions in theliterature of Germanic singing as “back, open,and dark” (or “covered”), and Italian singing as“front, closed, and bright” [1]. Although thepercepts of “back,” “open,” and “dark” wereuncommon, when they occurred they were mostlikely considered Germanic and were producedby area reductions in all vocal tract regions. Results specific to articulatory manipulationsare shown in Tables 1-3. These tables show thepercentage of ratings for which phrases werejudged as “medium” or “good” exemplars of theGerman versus Italian tonal ideals. In summary (see Tables), tokens judged asmedium or good exemplars of the German idealwere most often associated with narrower liparea and larger pharyngeal (phx) area than tokensrated as medium/good Italian exemplars. Tokensrated as medium/good Italian sounds were morefrequently associated with expanded oral cavity,as compared to tokens rated as medium/goodGerman exemplars.

Table 1. Percent of tokens judged as Germanicversus Italian, for lip changes.� lip area German Italian+100% 64% 45%+ 75% 67% 67%+ 50% 75% 83%+ 25% 100% 75%- 25% 92% 75%- 50% 67% 50%- 75% 67% 17%

Table 2. Percent of tokens judged as Germanversus Italian ideals, for oral area changes (�).� oral area German Italian+100% 50% 42%+ 75% 67% 42%+ 50% 75% 92%+ 25% 75% 92%- 25% 67% 58%- 50% 67% 50%- 75% 33% 25%

Table 3. Percent of tokens judged as Germanversus Italian ideals, for phx area changes (�).� phx area German Italian+100% 17% 17%+ 75% 33% 58%+ 50% 83% 67%+ 25% 67% 75%- 25% 75% 50%- 50% 45% 27%- 75% 42% 8%

ACKNOWLEDGEMENTS

Work supported by NIDCD K08 DC00139.

REFERENCES

1. Miller, R., English, French, German and ItalianTechniques of Singing, Scarecrow Press, Metuchen,N.J. 1977.

2. Taylor, M.H., Influences of Vocal Tract Shape onTonal Quality in the German and Italian Schools ofSinging, M.A. Thesis, University of Iowa, Iowa City,1996.

3. Titze, I.R., Mapes, S., and Story, B.H., J. Acoust.Soc. Am., 95, 1133-1142 (1994).

4. Story, B. H., Physiologically-Based SpeechSimulation with an Enhanced Wave-Reflection Modelof the Vocal Tract, Ph.D. Dissertation, University ofIowa, Iowa City, 1995.

5. Story, B.H., Titze, I.R., and Hoffman, E.A., J.Acoust. Soc. Am., 100, 537-554 (1996).

Acoustic Evaluation of the Reconstructionof Heinrich Mundt Pipe Organs in Prague

V. Syrový, Z. Otčenášek, J. Štěpánek

Sound Studio of the Faculty of Music, Academy of Performing Arts Prague,Malostranské nám. 13, 11800 Praha 1, Czech Republic, e-mail: syrovy@hamu.cz

The Baroque organ in the Church of Our Lady before Tyn in Prague (1670–73) was reconstructed in 1998–2000. Acousticmeasurement for documentation purposes was carried out before and after the reconstruction. The diagnostic method developedenables a detailed study of the plenum and its contributing stops. Results revealed that levels and contributions of lower plenumharmonics were preserved and that higher harmonics were strengthened owing to correction of Mixtur stops.

INTRODUCTION

The organ in the Church of Our Lady before Tyn inPrague, built by Heinrich Mundt in 1670–73, is amongthe most famous Baroque organs in Central Europe.The organ was reconstructed as part of long-termgeneral reconstruction of the church in 1998–2000. Itsoriginal specification was preserved together withoriginal pipes, as well as wind-chests and action. Thegoal of the reconstruction was to preserve the characterof instrument's original sound. Two acoustic measurements for documentationpurposes were carried out to enable comparison of theinstrument's sound on July 1992 before thereconstruction, and on September 2000 after thereconstruction. The documentation method used wasdeveloped in 1991-92 [1] especially for documentingacoustic properties of rare historical organs, includingmeasurement and diagnostic techniques.

METHOD AND RESULTS

The basis of the method is digital recording of thesound from all pipes of documented instruments androom acoustic measurement [1]. The quasi-stationaryparts of the tones are recorded by three microphonesplaced in the typical listening position in a church, 4 mabove the floor and with a 2-m span among them.Three neighbouring semitones (triads) are playedsimultaneously [2] and a mean amplitude spectrumalong with the time signal of the first microphone foreach triad is recorded. In addition to all pipe stops, aplenum sound of every organ machine is documented.The sampling rate adapts fluently to the stop footlength, as well as to the fundamental frequency incases of stops without repetition (sliding sample rate).This assures the same discrimination of tones in thespectrum of all triads. Two microphones measure the

starting transients of C-tones of all stops, one in theposition of triad measurement and one placed close tothe organist. The impulse responses measured by theMLSSA measurement system [3] are used to calculatefrequency dependence of reverberation time (Figure 1). It is possible to separate the harmonics of individualtones in each triad spectrum until the 6th harmonic andcalculate their levels. These values, established for thewhole range of the stop, enabled a detailed view of theproperties of the spectrum both in differentmeasurements (Figure 2) and among different stops.The sound character of the instrument is mostexpressive in the plenum. The Mundt Great Organplenum consists of octave and quint principal stops;thus in its spectrum the following harmonics dominate:1, 2, 3, 4, 5, 6, 8, 10, 12, 16, 20, 24, 32, 40, 48, 64, 80,96. Each of their frequencies fall into different third-octave bands if the band boundaries change accordingto fundamental frequency [4]. The levels of harmonicscalculated in the whole instrument range for everyplenum constituting stop were used for the assessmentof the contribution of these stops to the individualharmonic of the plenum, and thus enable examinationof the intoner voicing intentions. One can gain a moregeneral view of sound character by averaging levelsover the octave. Figure 3 gives an example of theresults of the diagnostic procedure for averaged valuesin octaves C3 and C4 of the Great Organ.

CONCLUSION

The results reveal that some reconstructed pipe stopshave better balanced levels of harmonics in the wholeinstrument range. Levels of lower harmonics of theplenum remained practically unchanged, including thesize of the contribution of individual stops. Thestrengthening of plenum levels of higher harmonics isrelated to the correction of Mixtur and Cembalo pipes.

FIGURE 1. Reverberation time in the Church of OurLady before Tyn measured before (1992) and after thechurch's reconstruction (2000).

ACKNOWLEDGMENT

The investigation was supported by the Ministry ofEducation and Youth (Project No. 511100001).

REFERENCES

1. Štěpánek, J., Otčenášek, Z., Syrový, V. (1994):Acoustic documentation of church organs,Proceedings of SMAC 93, Stockholm, 516-519.

2. Lottermoser, W., Meyer, J. (1966): Orgelakustik inEinzeldarstellungen, Verlag Das Musikinstrument.

3. Rife, D. (1987-90): MLSSA Reference Manual,Version 6.0, DRA Laboratories.

4. Štěpánek, J., Otčenášek, Z. (1995): Comparison ofpipe organ plenum sounds, Proceedings of ISMA95, Dourdan, 86-92.

FIGURE 2. Levels of the first (L1) and third (L3)harmonic of Bourdonflauta 16' closed pipe stop withleast square fit, before and after the reconstruction.

FIGURE 3. Mean levels of harmonics of Great organplenum and its constituting stops for octaves C3 andC4 before and after the reconstruction.

0

1

2

3

4

5

6

7

8

9

0.1 0.13 0.16 0.2 0.25 0.32 0.4 0.5 0.63 0.8 1 1.25 1.6 2 2.5 3.15 4 5 6.3 8 10

T [s]

1992 2000

f [kHz]

Reverberation Time

before the reconstruction

30

40

50

60

70

80

CD

EF

GA

BH

ccis

ddis

ef

fisg

gisa

bh

c1cis1

d1dis1

e1f1

fis1g1

gis1a1

b1h1

c2cis2

d2dis2

e2f2

fis2g2

gis2a2

b2h2

c3

L1L3

L [dB]

after the reconstruction

30

40

50

60

70

80

C2D2

E2F2

G2A2

Bb2B2

C3C#3

D3D#3

E3F3

F#3G3

G#3A3

Bb3B3

C4C#4

D4D#4

E4F4

F#4G4

G#4A4

Bb4B4

C5C#5

D5D#5

E5F5

F#5G5

G#5A5

Bb5B5

C6

L1L3

L [db]

0

20

40

60

80

1 2 3 4 5 6 8 10 12 16 20 24 32 40 48 64

O3 Octave L [dB]

harmonic [-]

f [Hz]200 500 1000 2000 4000 8000

after before

0

20

40

60

80H1L [dB]

a

before a

Prin

cipa

l 8'

b

Oct

ava

4' c

Q

uint

2 2

/3'

d

Supe

roct

ava

2' e

Q

uint

1 1

/3'

f

Sede

cim

a 1'

g

Mix

ture

VI 1

' h

C

emba

lo IV

2/3

'

0

20

40

60

80 H8L [dB]

fb

after

hgd

0

20

40

60

80 H12L [dB]

gb

after

hd ec

0

20

40

60

80H6L [dB]

eb

after

a gc h

0

20

40

60

80H4L [dB]

a b

after

gd

0

20

40

60

80H2L [dB]

a b

before

0

20

40

60

80H2L [dB]

a b

after

0

20

40

60

80H3

L [dB]

a c

after

0

20

40

60

80 H24L [dB]

f g

after

hd e

0

20

40

60

80H20L [dB]

d

after

g h

0

20

40

60

80 H16L [dB]

d

after

hgf

0

20

40

60

80H1L [dB]

aafter

0

20

40

60

80H3

L [dB]

a c

before

0

20

40

60

80H4L [dB]

a b

before

gd

0

20

40

60

80H6L [dB]

eb

before

a gc h

0

20

40

60

80 H8L [dB]

fb

before

hgd

0

20

40

60

80 H12L [dB]

gb

before

hd ec

0

20

40

60

80 H16L [dB]

d

before

hgf

0

20

40

60

80H20L [dB]

d

before

hg

0

20

40

60

80 H24L [dB]

f g

before

hd e

0

20

40

60

80 H32L [dB]

g

after

hf

0

20

40

60

80 H64L [dB]

g

after

h

0

20

40

60

80H48L [dB]

after

hgf

0

20

40

60

80H40

L [dB]

after

hgf

0

20

40

60

80 H32L [dB]

g

before

hf

0

20

40

60

80H40L [dB]

before

hgf

0

20

40

60

80H48L [dB]

before

hgf

0

20

40

60

80 H64L [dB]

g

before

h

0

20

40

60

80

1 2 3 4 5 6 8 10 12 16 20 24 32

O4 Octave L [dB]

harmonic [-]

f [Hz]400500 1000 2000 4000 8000

after before

0

20

40

60

80H1L [dB]

aafter

0

20

40

60

80 H8L [dB]

fb

after

hgd

0

20

40

60

80H12L [dB]

cb

before

hged

0

20

40

60

80 H12L [dB]

gb

after

hd ec

0

20

40

60

80H6L [dB]

a b

before

hgec

0

20

40

60

80H6L [dB]

eb

after

a gc h

0

20

40

60

80H4L [dB]

a b

after

gd h

0

20

40

60

80H1L [dB]

a

before

0

20

40

60

80 H2L [dB]

a bafter

g

0

20

40

60

80 H32L [dB]

f g

before

h

0

20

40

60

80 H24L [dB]

d e

before

hgf

0

20

40

60

80H16

L [dB]

fd

before

hg

0

20

40

60

80 H32L [dB]

f g

after

h

0

20

40

60

80H24L [dB]

ed

after

hgf

0

20

40

60

80H16

L [dB]

d

after

hgf

0

20

40

60

80 H8L [dB]

db

before

hgf

0

20

40

60

80H4

L [dB]

a b

before

d g h

0

20

40

60

80 H3L [dB]

a bafter

g

0

20

40

60

80 H3L [dB]

a bbefore

g

0

20

40

60

80 H2L [dB]

a bbefore

g

0

20

40

60

80H20L [dB]

d

after

hg

0

20

40

60

80H20L [dB]

d h

before

g