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Unit 1: Introduction to Sound I

1. What are the primary factors aecting the speed of sound in air? Absolute temperature

Molecular Mass of the gas

2. Briey dene each of the folloing a!e characteristics" and gi!e anappropriate unit of measure#

a. Amplitude Ma$imum sound pressure %&ascals'

b. (elocity )istance*+ime %metres*second'

c. ,re-uency umber of !ibrations per second %/ert0'

d. Wa!elength )istance beteen any to corresponding points %metres'

e. &hase

Where the graph begins on the $a$is % degrees or seconds'3. Briey distinguish beteen dB456" dB&W6" 7 dB4&6.

dBSIL8 4ound 5ntesity 6e!el is the o of energy through a units

area

10log10I actual

I ref

here 5 actual is the actual sound poer density le!el %in W m 2'here 5 ref is the reference sound poer le!el %19 12W m2'

dBPWL(SWL)8 4ound &oer 6e!el is the total poer radiated in all

directions by a source

10log10 W actualW ref

here W actual is the actual sound poer density le!el %in W'here W ref is the reference sound poer le!el %19 12W'

dBSPL8 4ound &ressure 6e!el is a ay of measuring and describing

the amplitude of a sound a!e at a particular point

20log10P actual

P ref

here & actual is the actual sound poer density le!el %in &a'here & ref is the reference sound poer le!el %29 : 19;&a < 29

=&a'

Unit 2: Introduction to Sound II

1. What is the result of combining to identical sine a!es ith a relati!e

phase dierence of 1>9 degrees? 9

2. With regard to the beha!iour of a!es" briey dene each of the folloing

terms#a. 4uperposition

Wa!es may pass through each other transparentlyb. )iraction

Wa!es may bend around obects

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c. @efraction Wa!es may change direction due to changing !elocity

d. Absorption Wa!e energy may be con!erted to !ibration or lost to friction

e. @eection

4ound is reected hen it hits a physical obecto Angle of incidence < angle of reectiono +ype 1# 4triing an immo!able obect*hard boundaryo +ype 2# Bounded to unbounded

f. )iusion Wa!es may scatter into multiple loer energy traectories

3. /o does the addition of correlated sounds dier from the addition of

uncorrelated sounds? orrelated sound sources#

o 4imply add pressures a!es together

Cncorrelated sound sources#

o Add the s-uares of the pressure a!es together and thens-uare root the result

Cse this e-uation to nd the pressure !alues hen gi!en dB !alues

to or out total dB#

P2=10

SPL

10 Pref2

Where &ref2ould be e-ual to D : 19 19

D. Why are sounds softer further aay from their source? +he energy in the sound a!e is spread more and more thinly as

the a!efront e$pands.E. What is meant by Facoustic impedanceF?

@atio of acoustic pressure to o %in !s out' almost lie resistance;. What is meant by dBA and dB" and hen is each appropriate to use?

dBA Aeighting is applied to instrumentmeasured sound le!els in

eort to account for the relati!e loudness percei!ed by the human

ear" as the ear is less sensiti!e to lo audio fre-uencies %C@(G'

Cse for orplace. db 8 eighting follos the fre-uency sensiti!ity of the human

ear at !ery hiHgh noise le!els %,6A++G@ C@(G' Cse for house

parties" here bass is craned up.I. What is the eect of mounting a loudspeaer in the corner of a room up

against the ceiling? Jutput is K dB more than if mounted in free space

>. Are four trombones tice as loud as to trombones? G$plain your anser.

Are tenty clarinets tice as loud as to clarinets? G$plain your anser. o" D trombones are not nearly tice as loud as 2 trombones. +he

same goes for the 29 clarinets !s 2 clarinetso +he doubling of instruments results in an addition of

appro$imately 3dB for each doublingo +he further aay the sound is" by the doubling of metres" loss

of appro$imately ;dB for each doubling

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K. A single (u!u0ela is measured as producing a sound pressure le!el of K2

dB4&6 at some arbitrary point in front of the player. onsidering that 2919

stadiums hold beteen E9"999 and 199"999 spectators" hat ould be the

cumulati!e 4&6 produced if e!ery one of 199"999 spectators ere to blo

at the same time? /o about if only an eighth of all 199"999 spectators

ere to be playing simultaneously? +o simplify you may assume that all(u!u0elas are being played from the same seat %disregard attenuation

o!er distance'. 199999" closest 2 poer is 1319I2%21I'

o +herefore appro$imate cumulati!e 4&6 ill be K2 H 3%1I' . Briey" ho should one interpret the legal limits relating to noise e$posure

in the Jccupational /ealth and 4afety Act %1KK3'? >9dB4&6 %or >EdB4&6%A'' o!er > hrs

H 3 dB for e!ery hal!ing of time

Cse the more accurate eighting cur!eK. Li!e an appro$imate 4&6 gure for each of the folloing en!ironments#a. Uuiet suburban home

3EdB4&6b. A noisy dance club

129dB4&619.What are the most common symptoms of damaged hearing?

Audiometric notch at D /0 is symptomatic of noiseinduced hearing

loss" as opposed to presbyacusis. Gar pain

@inging in the ear

&us or uid leaing from the ear (ertigo %especially if a result of diseases such as acoustic neuroma'

11.omplete the folloing# the dierence" in decibels" beteen the softest

and loudest sounds a system can produce is called the VVVVVVVVVVVVVVVVVVV

of the system. @ange

12.Briey e$plain the primary mechanisms hereby humans distinguish the

direction from hich a sound originates. 5nteraural +ime )ierence 8 Which ear hears the sound rst

5nteraural 5ntensity )ierence 8 Which ear hears the sound louder13.)istinguish beteen delay stereo" intensity stereo" and binaural stereo.

)elay stereoo @ecording made ith to microphones placed parallel" a

small distance apart 5ntensity stereo

o @ecording made ith to microphones placed together but at

an angle to each other Binaural stereo

o @ecording made ith to microphones placed either side of a

dummy head

Unit 6: Notes Har!on" I

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1. Briey e$plain hy some naturally occurring sounds ha!e a recogni0able

pitch" hile others donRt. &itches are sounds consisting mostly of fre-uencies that ha!e a

common factor. ot e!ery naturally occurring sound has fre-uencies

ith common factors

2. Briey dene the term TtimbreR ith reference to the natural harmonicseries.

5f the pattern of !ibration on the basilar membrane !aries hen

comparing dierent sounds" for e$ample from a !iolin and a

clarinet" then the sounds are percei!ed as ha!ing a dierent

OtimbreP3. Li!e the letter name %pitch' of the se!enth harmonic abo!e the

fundamental ). )

D. A perfectly cylindrical pipe" hen blon" sounds the pitch L. 5f a -uarter of

this pipe is cut o" hat pitch ill the remaining section of pipe soundhen blon? )?

Unit #: Notes Har!on" II

1. /oard mentions three mechanisms hich ha!e been considered at some

time to account for the O&lace +heoryP of pitch perception" namely loest

fre-uency present" smallest linear gap and highest common factor. Briey

e$plain ho each of these has been dis-ualied" and hich one best

accounts for human pitch perception.

6oest fre-uency present#o 6ocating the fundamental fre-uencyo )ismissed by e$perimentation ith spectra lacing a

fundamental 4mallest linear gap#

o ,inding the smallest fre-uency dierent beteen adacent

harmonicso )oes not account for oddharmonic only spectra

/ighest common factor#o ,inding the /, of components presento ,ails to account for 4choutenRs T!irtual pitchRo +/54 JG BG4+ AJC+4 ,J@ /CMA &5+/ &G@G&+5J

2. Which aspects of human pitch perception are not accounted for by the

O&lace +heoryP of pitch perception? +he ne degree of accuracy of human hearing

&erception of sounds hose fre-uency components are not resol!ed

by the place mechanism +he pitch percei!ed for some sounds hich ha!e continuous %non

harmonic' spectra &itch perception of sounds ith fundamentals less than E9/0

@esolution of harmonics abo!e Ith

3. +he ords TpitchR and Tfre-uencyR are idely held to mean the same thing"though they actually refer to dierent things. G$plain the dierence

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beteen these to terms" gi!ing e$amples of ho TpitchR perception might

be inuenced by factors other than ust Tfre-uencyR. &itch is our perception of a sound and fre-uency is the physical

ocillations in!ol!ed in producing and maintaining that note. /igher

pitches correspond to higher fre-uencies.

Unit $: Notes Har!on" III

1. /o is the harmonic series typically used to e$plain the e!olution of

estern harmony? +he e!olution of Western /armony %in hat harmonies are

acceptable' follos the pattern of ascending the harmonic serieso Jcta!eo ,iftho ,ourtho Maor +hird

o Minor +hirdo Minor +hird %)imished ,ifth?'o Maor second %)ominant 4e!enth?o Maor thirdo Maor third %Augmented ,ifth?'

2. )escribe the most important features of the graph of percei!ed

consonance and dissonance produced by &lomp 7 6e!elt. When the fre-uencies are e-ual %unison' the tones are udged to be

Operfectly consonant.P When their fre-uency dierence is greater than one critical

bandidth" they are udged consonant. ,or fre-uency dierences of beteen E and E9S of the critical

bandidth the inter!al is dissonant. Ma$imum dissonance occurs hen the fre-uency dierence is a

-uarter of a critical bandidth.3. G$plain the acoustic phenomenon of TbeatsR" commonly heard as

instruments are being tuned. What is actually happening to cause this

beha!iour? A !ibration is basically oscillation beteen to fre-uencies %,1 and

,2'. When ,1 is e-ual to ,2" a single note is heard. As soon as ,2 is

mo!ed higher or loer than ,1 a sound ith clearly undulating

amplitude !ariations non as ObeatsP is heard

Unit %: Notes Har!on" I&

1. What is the &ythagorean comma? +he ratio of tel!e &ythagorean fths to se!en octa!es.

2. What is the syntonic comma? +he ratio of a &ythagorean maor third against a ust maor third.

3. Briey e$plain the term TcentR" as coined by Ale$ander . Gllis.

+he e-ual tempered semitone is subdi!ided into Ocents"P here one

cent is one hundredth of an e-ual tempered semitone

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D. Briey e$plain the fundamental inno!ation underlying meantone

temperament. +he meantone scale consists of ust maor thirds %E#D'" e-ualsi0ed

hole tones" and fths hich are tuned slightly atter than the pure

fth

E. Li!e to names associated ith the de!elopment of meantonetemperament.

Qarlino

,rancis 4alinas;. Li!e one e$ample of a TolftoneR.

G and ,X on the celloI. What ould be the fre-uency of the note that lies a &ythagorean fth

belo 1.2 Y/0? >99/0

>. G$press the modern e-ual temperament semitone as a ratio or fraction.

K. Mention one ad!antage and one disad!antage to the use of e-ual

temperament. Ad!antage# All eys are e-ually useable

)isad!antage# o inter!al is intune in relation to the inter!als

beteen adacent members of the natural harmonic series.

+herefore none is perfectly consonant.

19.omplete the folloing table for a ust diatonic scale built on #

Note

Name C D E F G A B C

Ratio 1/1 9/8 5/4 4/3 3/2 5/3 15/8 2/1

Natural 24 27 30 32 36 40 45 48

Cents 0 204 386 498 702 884 1088 1200

Step Name T t s T t T s

Ratio 9/8 10/9 16/15 9/8 10/9 9/8 16/15

Cents 204 182 112 204 182 204 112

https://en.wikipedia.org/wiki/Natural_(music)https://en.wikipedia.org/wiki/Natural_(music)

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11.omplete the folloing table for a &ythagorean diatonic scale built on #

Note C D E F G A B C

Ratio 1/1 9/8 81/64 4/3 3/2 27/16 243/128 2/1

Step 9/8 9/8 256/243 9/8 9/8 9/8 256/243