Data on maximum speed of pitch changes - KTH...Pitch changes can be regarded as manifestations of...
Transcript of Data on maximum speed of pitch changes - KTH...Pitch changes can be regarded as manifestations of...
Dept. for Speech, Music and Hearing
Quarterly Progress andStatus Report
Data on maximum speed ofpitch changes
Sundberg, J.
journal: STL-QPSRvolume: 14number: 4year: 1973pages: 039-047
http://www.speech.kth.se/qpsr
STL-QPSR 4/1973
B. DATA ON MAXIMUM SPEED O F PITCH CHANGES
J. Sundberg
Abstract
The maximum speed of voice pitch changes is measured in male and female s ingers and untrained subjects. Typical differences a r e observed between each of these four groups. On the average s ingers change the pitch m o r e quickly a s compared with untrained subjects. The same observation i s made regarding female subjects a s compared with male subjects. Unlike s ingers , untrained subjects perform pitch drops considerably fas te r than pitch elevations. The implications with respect to the propert ies of the pitch changing mechanisms a r e discussed.
Introduction
Pitch changes can be regarded a s manifestations of the pitch regulat-
ing system and can be assumed to m i r r o r the propert ies of this system.
The character is t ics of pitch changes performed a s quickly a s possible
by untrained speakers have been examined by Ohala (1972) and Ohala
and Ewan (1972). Singers can be assumed to use the pitch regulating
system with maximal efficiency. Therefore, an investigation of maximal-
ly fast pitch changes in s ingers may complement our knowledge about the
system in various respects . The purpose of the present paper was to
collect data on the maximal speed with which pitch can be changed in
s ingers and untrained subjects of both sexes.
Subjects-
The untrained subjects (six females , five males) participated in a one-
week voice training course. None of the subjects had abnormal voices,
and some of them had had modest experience singing in a chor. The
trained subjects (four females , five males) represented a group of highly
experienced singers. All of them had had severa l yea r s of voice t rain-
ing, and most of them presently work a s ope r a and concert singer s.
Experimental procedure
The subjects were asked to al ternate repeatedly between two given
pitches, and thereby to perform the pitch changes a s rhythmically and
a s quickly a s possible. The rhythm periodicity was signalled to the
subjects in slightly differing ways: by the exper imenter ' s counting
combined with distinct hand movements, o r by clicks in e a r phones
STL-QPSR 4/1973
combined with flashes of a small lamp. In this way, the interval
singing resembled a legato performance of the sequence of notes
schematically indicated in Fig. 11-B- I . At least 8 repetitions of
each pitch change were secured from each subject. The intervals
sung were an octave, a fifth, a major third, and in some cases
a l so a major second. These intervals correspond to a frequency
ratio of 1:2, 1:1.5, 1:1.25, and 1:1.12, respectively. Each sub-
ject s tar ted a l l intervals f rom the same lower pitch which lay in
the lower par t of the subject ' s range. The signal was recorded on
tape.
Fig. 11-B - 1. Schematical representation of the interval singing.
-
Measurements
The fundamental frequency was measured by means of a low
pass fi l ter connected to a zero-crossing detector. The output was
regis tered on a n oscillograph using a paper speed of 100 mm/sec.
etc .
L
A typical example of the registrations is given in Fig. 11-B-2.
3 * * (I, d
In this figure the measurement of the transient durations i s a l so I
1 i l lustrated. In each sample the s t a r t and end frequencies were
determined. Those points on the curve that represented 1/8 and
a 0
7/8 of the difference between the s t a r t and end frequencies were
identified. The time interval separating these two points was de-
0 *
fined a s the response t ime in accordance with the procedure chosen
by Ohala and Ewan (1972). Thus, the response t ime is the t ime
needed by the subject in o rde r to produce 6/8 of the pitch change.
In most cases the s ingers displayed a vibrato, i. e. the quasi-
stationary frequencies showed a regularly oscillating value. In
these cases the s t a r t and end frequencies were defined a s the
STL-QPSR 4/1973
seems to suggest that the auditory feedback provides information of r e -
levance to the synchronization of vibrato speed and pitch changes. How-
ever , a l l subjects did not adjust the vibrato speed in accordance with the
given tempo. In some cases the vibrato simply disappeared o r the tempo
was not maintained.
Results
A s the response t ime in this experiment was defined in the same way
a s in the investigation of Ohala and Ewan (1972) , our resu l t s should be
comparable to the i rs . In Fig. 11-B-3 the averages f rom our group of un-
trained male subjects can be compared with the data given by Ohala and
Ewan which pertain to the same type of subjects. There may be a slight
tendency for our subjects to perform pitch elevations m o r e quickly.
However, this difference i s presumably due to the fact that in our m e a s -
urements each subject' s slowest transit ions were disregarded. Apart
f rom this small difference, the agreement between the two se ts of data
is good. This agreement supports the assumption that our group of un-
trained ma les was representative, and that the differences in the ex- ~ perimental procedures between the two investigations did not affect the
resul ts .
Fig. 11-B-4 compares the averages of the male and female group of
untrained subjects. Mainly, the two pa i rs of curves simply paral le l
each other. This implies that the female and ma le groups show a s im-
i l a r dependence of interval width, but the female group has the shorter
response t imes. In both groups the response t ime grows with interval
width, particularly in the case of rising intervals. Fur the r , the rising
intervals have slower response t ime values than falling intervals.
In Fig. 11-B-5 the female group of untrained subjects i s compared
with the averages pertaining to the individual female singers. Regarding
the rising intervals two differences can be observed between the groups.
F o r the s ingers the response t ime i s shor te r , and the dependence on
interval width i s slightly smaller . A s r ega rds the falling intervals the
differences between the groups a r e smal le r eventhough the s ingers show
somewhat shorter response t imes. Thus, in the case of female s ingers ,
the t rend to slow pitch r i s e s and rapid pitch drops is much l e s s pro-
nounced than in the group of untrained.
UNTRAINED MALES
RISING
INTERVAL WIDTH (semitones)
FALLING
Fig. 11-B-3. Response t i m e values given by Ohala & Ewan (1972) (points) and the ave r ages obtained fo r our g roup of untrained m a l e subjects . The b a r s r ep r e sen t the s ca t t e r in t e r m s of + one s tandard deviation.
200
150
-
-
UNTRAINED MALE AND FEMALE
4 6 8 10 12 4 6 8 10 12
l NTERVAL WIDTH (sernitones)
Fig . 11- B - 4 . Averaged response time values for untrained male (solid line) and female (dashed line) subjects.
FEMALE TRAINED Ai\iD UNTR/"+lli\lED
2 4 6 8 10 12 2 4 6 8 10 12
INTERVA L WIDTH (semitones)
Fig. 11-B-5. Response t ime of f ema le s i nge r s . Each symbol r e f e r s to a given subject . The solid l ines show the ave r age response time of the group of female untrained subjects .
STL-QPSR 4/1973
Fig. 11-B- 6 allows the corresponding comparison with respect to
male subjects. Evidently, considerable differences a r e found in the
dependence on interval width among the singers. However, a s in the
female voices, the average response t ime i s shorter in the s ingers than
i n the untrained subjects, particularly i n r is ing intervals .
In Fig. 11-B-7 the averages obtained f rom each of the four groups of
subjects m a y be compared. In r is ing intervals the s ingers have fas te r
transit ions and the response t ime grows l e s s with increasing interval
width. With falling intervals we observe that the s ingers seem to show
a somewhat grea ter dependence on interval width, and that female s ingers
have somewhat fas te r transit ions than untrained voices. In both types of
intervals the female subjects give shorter response t ime values than
male subjects. Thus, there seems to be differences in the response t ime
between all of the four groups included in this investigation: between
ma les and females , and between untrained subjects and s ingers .
Discussion
Recently Ohala (1972) and Ohala and Ewan (1972) have suggested an
explanation for the asymmetry in the response t ime between rising and
falling intervals. F i r s t , they in terpre t the rapid pitch drops a s an in-
dication that pitch i s lowered actively. Our resu l t s support the same
conclusion. Second, in o rde r to explain why larynx height and pitch show
an interdependence in several subjects, they suggest that a high larynx
tenses the vocal folds in a ver t ical dimension. To quote Ohala and Ewan:
"The difference in t ime taken to r a i se and lower pitch could be explained
if we could show that the anter ior-poster ior tensing mechanism was
fas tes t for raising pitch and the vert ical tensing mechanism fastest for
lowering pitch". Thus, according to these authors , the fas t performance
of pitch drops may possibly be explained if the pitch dependent ver t ical
movements of the larynx a r e taken into account.
In singing, pitch dependent shifts in larynx height probably cannot be
accepted. This assumption i s supported not only by an overwhelming
agreement on this point among singing teachers , but a l so by the fact that ! a high larynx position i s likely to distroy the "singing formant", which /
I evidently i s a desirable character is t ic of professional singing, the
soprano voice possibly excepted ( ~ u n d b e r g 1972 and 1974). Also, formal
MALE TRAINED AND UNTRAINED
INTERVAL WIDTH (semitones)
Fig. 11-B-6. Response t i m e of m a l e s i n g e r s . E a c h symbol r e f e r s t o a given subjec t . The solid l i nes show the a v e r a g e r e s p o n s e time of the group of m a l e un t ra ined subjec ts .
RISING FALLING I I I I I
120 - -
loo - - r .
INTERVAL WIDTH (semitones)
Fig. 11-B-7. Average response t ime of male (filled c i rc les ) and female (open circles) untrained subjects (dashed l ines) and s ingers (solid l ines).
STL-QPSR 4/1973 44.
measurements of the dependence of larynx height on pitch in professional
s ingers support the conclusion that this dependence decreases with the
singers ' skil l (Frommhold and Hoppe 1965). Nevertheless, s ingers
were observed to perform pitch changes fas te r than untrained subjects.
Thus, if larynx height i s causually related to the speed of pitch changes,
this relationship seems to be ra ther complex.
Pitch changes a r e due to movements in s t ruc tures in the larynx from
one given position to another given position. In most fast and voluntary
movements of human s t ruc tures from one given position to another, two
antagonistic muscle functions a r e involved. With respect to a specific
movement, one group plays the role of an accelerator : by contracting it
accelerate the s t ructures toward the target position. The other muscle
group plays the role of a decelerator: i t decelerates the moving t issue
so that i t stops a t the target position and does not pass it. The maximum
speed with which the s t ructure can be moved between two given positions
probably depends on severa l factors. Among these we may as sume that
the following a r e important for fast changes in the voice pitch. One i s
the force per unit of m a s s to be moved, that the muscles involved develop.
Probably, the force of the accelerator i s m o r e decisive to the maximal
speed of movement than the force of the decelerator . Another factor
must be the t ime constants characterizing the feedback system used for ~ controlling the position of the moving s t ructure. A third factor may be
the contraction range of the muscles involved a s compared with the
contraction minimally required for the actual movement.
These considerations may help u s to find hypothetical explanations to
the differences in response t ime values that have been found above. Let
u s s t a r t by considering the asymmetry between rising and falling intervals, I
An important pitch-raising muscle i s the crico-thyroideus, According 1 I
to some authors , pitch can be lowered by contracting the thyro-arytenoi-
deus la te ra l i s (van Riper and Irwin, 1958 , Zemlin,. 1968 , Lindqvist, 1972).
If this muscle i s assumed to lower the pitch, the narrowing of the larynx
tube opening typically occurring when pitch i s lowered can be explained.
Thus, according to Lindqvist (1972), this muscle not only shortens and i laxes the vocal folds, but a lso constricts the larynx tube. Therefore, i t
can be said to have the function of protecting the larynx and the lungs.
Protecting muscles can be assumed to be well developed and quick in
cl ., ' .
STL-QPSR 4/1973
operation because of their importance to vital functions, If so , the
thyro-arytenoideus la te ra l i s must be assumed to be well developed and
quick in operation in a l l subjects regardless of training. The cr ico-
thyroideus does not possess a protective function. Therefore we may
assume that this muscle may be developed by training. The differ - ence in response t ime between s ingers and untrained subjects i s much
l a rge r in pitch elevations than in pitch drops. If we as sume that the
strength of the accelerator i s m o r e important to the speed of the move-
ment than the decelerator strength, this difference between s ingers and
untrained subjects becomes under standable. I t would reflect the con-
sequences of an increase of the force per unit of m a s s to be moved
developed by the crico-thyroid muscle , the accelerator in pitch eleva-
tions. The sex differences in response t ime values m a y ve ry well be
due to the same effect. If so, we would expect to find a pitch regulating
system which develops m o r e muscle force per unit of m a s s to be moved
in females than in males .
The differences in response t ime may ve ry well be due to m o r e than
one thing. The feedback system used for controlling the "position"
along the pitch scale may differ between s ingers and untrained subjects.
We may as sume that untrained subjects re ly to a higher degree on a slow
auditory feedback system than s ingers do. Singers may re ly more on a
sor t of "muscle memory" developed during the training. They "remember"
how much and when the various muscles must contract in o rde r for the
pitch to go f rom one given value to another. This ability to explore and
memorize the function of a muscle system seems to be of grea t relevance
in other fo rms of music playing. F o r instance, unlike the l ea rne r , the
professional pianist does not need to follow the finger with h is eyes in 1 orde r to hit a far-lying note on the key-board. By experience developed
during practice he "knows" exactly how much and when the relevant
muscles shall contract. I t seems likely that this ability to memorize I muscle positions and contractions i s developed and used a lso in singing.
The ability may in par t be responsible for the differences between s ingers
and untrained subjects. However, i t d o t s not explain a l l differences.
F o r instance, i t does not explainwhy the response t ime differences a r e
greater in rising than in falling pitch intervals.
STL-QPSR 4/1973 46.
The importance of the contraction range of the relevant muscles to
the speed of pitch changes may be studied by varying the frequency level
of the intervals systematically within the subjects' range. Such ex-
periments were not included in the present investigation. Therefore
this question must be left open for future research . .
The vibrato i s frequently assumed to be due to a self-oscillation of
the pitch regulating system. The frequency of these oscillations would
then depend on the t ime constants inherent in the pitch regulating system.
But these same time constants also manifest themselves in the response
time of pitch changes. Therefore, an interrelationship between the speed
of the vibrato and the response time in pitch changes might be expected.
Our resul t s did not show any interrelationship of this kind, though. F o r
instance, in the experiments with varied tempi, the vibrato periodicity
changed, whereas the response time values remained essentially the
same. F r o m these data i t seems safe to conclude that the vibrato gen-
erating system is not identical in a l l pa r t s with the pitch regulating sys-
tem.
The explanations suggested above to the response time differences
between the groups of subjects a r e certainly speculative. This seems to
be an inevitable consequence of the limited knowledge that we possess
about the pitch regulating system. I t is likely that this knowledge will
increase substantially when models have been worked out for the system
which controls, adjusts, and generates the voice pitch.
Conclusions
The data collected in the present investigation indicate that there a r e i
typical differences between various groups of subjects regarding the I I transient t ime required to complete changes of the voice pitch. Female I
subjects perform pitch changes fas ter than 1 ~ 1 a l e subjects, and s ingers
change the pitch f a s t e r than untrained voices. In untrained voices, pitch I
I
elevations take longer t ime than pitch drops, whereas this difference is
much l e s s pronounced o r even absent in singers. The dependence of I
the response time on the interval width var ies considerably between sub-
jects. The general trend i s , however, that the response time increases
slightly with interval width, particularly in the case of untrained sub-
jects performing pitch elevations. Hypothetically, the differences between