Lecture 1 Acoustic Fundamentals

8/16/2019 Lecture 1 Acoustic Fundamentals

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AcousticsFundamentals


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hat is ACOUSTICS?

“akouein”

It is the science of sound,

including its poduction,popagation and e!ects"

It is also de#ned as thegeneation, tansmission,and eception of eneg$ in

the fom of %i&ational


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(ain Su&)*iscipline of Acoustics

is the stud$ of aeod$namicsound, geneated 'hen a +uid +o'inteacts 'ith a solid suface o

'ith anothe +o'

AEROACOUSTICS

ARCHITECTURAL ACOUSTICS

BIOACOUSTICS

is the stud$ of ho' sound and&uildings inteact

is the stud$ of the use of sound&$ animals such as 'hales,

dolphins and &ats"


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is the stud$ of the use of sound inmedicine"

BIOMEDICAL ACOUSTICS

LOUDSPEAKER ACOUSTICS

PSYCHOLOGICAL ACOUSTICS

is the engineeing discipline &ehind

the design of the loudspeake"

is the stud$ of ho' people eact tosound, heaing, peception and

localiation"

is the stud$ of the mechanical,electical and &iochemical function of

heaing in li%ing oganisms"

PHYSIOLOGICAL ACOUSTICS


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PHYSICAL ACOUSTICS

STRUCTURAL ACOUSTICS ANDVIBRATION

is the stud$ of the detailed inteactionof sound 'ith mateials and +uids SONOLUMINESCENCE and

THERMOACOUSTICS

is the stud$ of ho' sound andmechanical stuctues inteact

MUSICAL ACOUSTICS

is the stud$ of the ph$sics of musicalinstuments"

SO-O.U(I-/SC/-C/)the emission of light &$

&u&&les in a li0uid e1cited &$sound

T2/3(OACOUSTIC

S



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is the stud$ of ho' sound isgeneated and measued &$loudspeakes, micophones, sonapo4ectos, h$dophones, ultasonic

tansduces, sensos"

TRANSDUCTION

WOLFFIAN ACOUSTICS

UNDERWATER ACOUSTICS

is the stud$ of salient featues ofpediatic ultasound

is the stud$ of the popagation ofsound in oceans"



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is the stud$ of high fe0uenc$ sound

ULTRASONICS

ENVIRONMENTAL NOISE

SPEECH COMMUNICATION

is the stud$ of the soundpopagation in the humanen%ionment, noise health e!ects andnoise mitigation anal$sis"

the stud$ of ho' speech is poduced,the anal$sis of speech signals and thepopeties of speech tansmission,

stoage, ecognition and enhancement"



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ACOUSTICAL MEASUREMENTSAND INSTRUMENTATION


ACOUSTICS SIGNAL PROCESSING

ACOUSTICAL ENGINEERING


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3C2IT/CTU3A. ACOUSTIC

is a special &anch of science thatdeals 'ith the constuction ofenclosed aeas so as to enhance theheaing of 'anted sounds"

(A3CUS5IT3U5IUS

6O..IO

7OS/622/-38

WA..AC/ C./(/-T

SA9I-/“Fathe of (oden Achitectual


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hat is SOU-*?

is a ph$sical phenomenon thatstimulates the sense of heaing" It isan aual sensation caused &$ pessue+uctuations"

is a tem sometimes esticted tosuch ai&one %i&ational 'a%es,ho'e%e, moden ph$sicists usuall$

e1tend the tem to include simila%i&ations in othe gaseous, li0uid, osolid media"

is elemental that po%ides all sots ofco niti%e and a!ecti%e infomation"


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Speed of Sound

It is a pessue 'a%e that popagatesthough ai 'ith a speed of

appo1imatel$:

;;<mete=second


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Speed of Sound

In fuid dynami!" #$% !&%%d '( !'und ina fuid m%dium )*a! '+ ,i-uid. i! u!%d a!a +%,a#i/% m%a!u+% ('+ #$% !&%%d '( an

'01%# m'/in* #$+'u*$ #$% m%dium2 T$% !&%%d '( an '01%# di/id%d 0y #$%!&%%d '( !'und in #$% fuid i! a,,%d #$%

(ach num&e2

O01%#! m'/in* a# !&%%d! *+%a#%+ #$anMach1 a+% #+a/%,in* a# !u&%+!'ni

!&%%d!2


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Categoies of Sound

(USIC-OIS/

S6//C

2

/%e$thing aual

can &e gouped into thee categoies:


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Atti&utes of Sound

6ITC2 the atti&ute of audito$

sensation in tems of 'hich soundma$ &e odeed on a scalepimail$ elated to fe0uenc$"

highness o lo'ness of a musicaltone as detemined &$ the apidit$of the %i&ations poducing it"

UNIT3(/.

6oposed 9$:

ST/5/-S, 5O.>(A-- A-*-/W(A-- @;B

4"555 M%,! i! #$% &i #$ '( 4"555 H6 #'n% a# a!%n!a# i'n ,%/%, '( 75dB

The pitch of an$ sound 4udged &$listenes to &e “n” times that of a (/.

TO-/ is “n mels”"


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Atti&utes of Sound

.OU*-/SS is an o&se%eDs audito$

impession of the stength ofsound"

.oudness .e%el is measued &$the sound pessue le%el of astandad pue tone of speci#ed

fe0uenc$ 'hich is assessed &$

62O- i! #$% uni# '( ,'udn%!! ,%/%, 8$%n3

a2 T$% !#anda+d &u+% #'n% i! &+'du%d 0y a!%n!i0,y &,an% !inu!'ida, &+'*+%!!i/% !'und

8a/% 'min* (+'m di+%#,y in (+'n# '( #$%'0!%+/%+ and $a/in* a (+%-u%ny '( 4555H62

02 T$% !'und &+%!!u+% ,%/%, in #$% (+%%

&+'*+%!!i/% 8a/% i! %9&+%!!%d in dB a0'/%; ;

SO-/ i! #$% uni# '( ,'udn%!! 'n a !a,%d%!i*n%d #' *i/% !a,% num0%+! a&&+'9ima#%,y&+'&'+#i'na, #' #$% ,'udn%!!2

F'+ &+a#ia, &u+&'!%!" #$% !a,% i! &+%i!%,yd%?n%d 0y i#! +%,a#i'n #' #$% &$'n !a,%2

62O- E < G @< log H SO-/

UNIT3 62O- andSO-/


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Atti&utes of Sound

TI(93/ TO-/ CO.O3

is the chaacteistic tonal 0ualit$of sound

6U3/ TO-/ i! a !'und in 8$i$ #$% !'und&+%!!u+% /a+i%! !inu!'ida,,y 8i#$ #im%2

T$% 8a/%('+m may 0% +%&+%!%n#%d 0y a !in%

8a/%2


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Atti&utes of Sound

T/(6O

is the speed of sound

ho' fast o slo'


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Atti&utes of Sound

328T2(

elates to a sonic time patten,ma$ &e simple, constant, comple1o changing"


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Atti&utes of Sound

ATTAC>

is the 'a$ sound &egins

can &e had, soft, cisp o gadual


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Atti&utes of Sound

*U3ATIO-

efes to ho' long a sound &lasts

can &e shot o sustained sounds


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Atti&utes of Sound

*/CA8

efes to ho' fast sound fadesfom a cetain loudness

can &e 0uick, gadual o slo'


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Sound eneation

T3A-S(ITTI- (/*IU(

63/S/-C/ OF 5I93ATIO-3/C/I5/3 O3 /-* US/3

3e0uiements to 6oduceSound


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-atue of SoundSound is the sensation poduced &$ the

ea 'hen stimulated &$ a %i&atingo&4ect though a se0uence ofcompessions and aefactions in the aisuounding it"

CO(63/SSIO-)condensed egion of the mediumthough 'hich a longitudinal 'a%e

ta%els"3A3/FACTIO-)ae#ed egion o egion of

lessened pessue of the medium

though 'hich a longitudinal 'a%e


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O97/CTI5/.8:a puel$ phenomena consisting of'a%e motion in ai o an$tansmitting medium

Intepetation of Sound

SU97/CTI5/.8:

the sensation poduced &$ outsidestimulation on the ea"


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:5


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5elocit$ of 6opagation

Sound ta%els at di!eent%elocities depending upon themedium"

Since sound ta%els not onl$ in ai&ut also though pats of the

stuctue, it is of inteest to kno'the %elocities in othe media"


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I- A AS (/*IU(:

s E

'hee:6o E is the stead$ pessue of the gas in -=mJHK E is the stead$ o a%eage densit$ of the gas in

kg=mJ; E atio of the speci#c heat of constant pessue to

that of the constant %olume


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I- -O3(A. *38 AI3:

s E ;;@"L G


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I- .IPUI*:

s E

'hee:> E li0uid compessi&ilit$ m)sJH=kg )

CO-STA-T

E B1@


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(ach -um&e

/3-ST (AC2

/3-ST WA.*F3I/* 7OS/F W/-R/.(AC2


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A!!i*nm%n#3

• Li!# ai++a(#! #'*%#$%+ 8i#$ #$%i+ Ma$Num0%+!

• A&&,ia#i'n! Mi,i#a+y" C'mm%+ia,"%#2

• Ima*%!

• D%/%,'&%+!

• L%n*#$ '( S%+/i%


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-atue of Speech

SOU-* 63/SSU3/ WA5/ OF S6//C2:

@


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A!!i*nm%n#3•

Ta0u,a#% !'m% !'und !'u+%! 8i#$#$%i+ 'm&u#%d &'8%+ and #$%i+'++%!&'ndin* !'und &'8%+ ,%/%," indB" +%(%+%n%d a# 454: 8a##!2

• E9am&,%3

(ust&edi!eent fom

thegi%endata inthe

handou

h


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Speech (easuement

5U (/T/3:It is the de%ice used to measue

speech %olume and designed to follo'speech le%els in elation to humanheaing 'ith a standad signal le%el ofGd9m on a M/3 O5/3 T2/C2A--/. d9m

6d9m E 5U eading V @" d9 G @<

Cl f S h


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Classes of Speech

5OIC/* SOU-*SAe poduced 'hen ou %ocal chods %i&ate as a

esult of ou lungs geneating sucient pessue toopen ou %ocal folds" Fo most people, the %i&ationfe0uenc$ of thei folds is 'ithin L< to


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Fe0uenc$ 6aametes

2A3(O-ICS

the integal multiples of thefundamental fe0uenc$

-th 2amonics E - 1Ff

F 6 t


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Fe0uenc$ 6aametes

O5/3TO-/

musical tem fo hamonics

-th O%etone E -G@1 Ff

F 6 t


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Fe0uenc$ 6aametes

OCTA5/fe0uenc$ inte%al of HIt is an inte%al &et'een t'ofe0uencies that ha%e a tonal ation of H

to @"It has a pitch inte%al of H:@It is the tone 'hose fe0uenc$ is t'icethat of the gi%en tone"

-th Octa%e E HJ- 1Ff -um&e of Octa%e E logH


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F 6 t


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Fe0uenc$ 6aametes

The human heaing ange fom H< 2to H< k2 has appo1imatel$ @< octa%e&ands"

The @< octa%es ae categoied as:

9ASS @st to th

(I*3A-/ Lth to Qth

T3/9./ th and @


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5ocal 3ange

5ocal 3ange


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5ocal 3ange

Appaent .oudness and .oudness


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Appaent .oudness and .oudness.e%el

.OU*-/SS

./5/.

A66A3/-T

.OU*-/SS5/38FAI-T

FAI-T(O*/3AT/

.OU*5/38.OU*

*/AF/-I-

< to @L d9

@L to ;< d9

;< to M< d9

M< to Q< d9

Q< to @;<d9

@;< d9


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Appaent .oudness and .oudness.e%el

T23/S2O.* OF2/A3I-

A5/3A/

CO-5/3SATIO-

T23/S2O.* OF 6AI-

6/3(A-/-T *A(A/TO 2/A3I-

< d9

M< d9

@H< d9

@L<

d9 S6. of Common Sound Souce


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S6. of Common Sound Souce

SOU3C/ S6. d9


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Sample 6o&lems

*etemine the speed of sound in ai atST6"-OT/ XST6:

E @" fo ai, E @"Hkg=mJ;,6 E @ atm

E @"


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Sample 6o&lems

A camea focuses using ultasound" If itfocuses pecisel$ at H< degee Celsius,ho' fa o! Y 'ill it &e at < degeeCelsius?

;"L;Y

Sample 6o&lems


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Sample 6o&lems

A +ute 'ith all of the holes closed can&e consideed as a tu&e 'ith &oth endsopen" It has a fundamental fe0uenc$ ofHM@"M 2 'hich is the middle C”"

Calculate the ;d

hamonic, ;d

o%etone,;d octa%es, and ;d decades of thefundamental fe0uenc$ calculated"

;d hamonic E BQ"Q

2;d o%etone E @"


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AcousticsFundamentals

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Lecture 1 Acoustic Fundamentals