Download - Akustik bei Alexis Baskind am 04.04.2011
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) $peed *f$peäd sf sound
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3.4
Fundamentals of Acoustlcs !The Soundke
üutiltne
,4st,.u" ri
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L r What is ä snund wäve ?
Z r speed of süund
3 - Sound as an üscillati 0n
4 r 5uperpüsitfün principle
5 - Süund pressuil"e level
6 r Distance law
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7. ffi Speed of soundI Srsed sf $$Hnd is n$t $sund pärticle uelucity II, r:ttgifrxlini*il l1tftr'*
*>The pärttnl*s äre üsciNlating with a väriahleveilscity {a.k,a* "*ressure grädient"} ärüund astable positi *n {if there's n$ wind in cäse nf nir f }
ffiüF Th* i..j1'.'":ji*;ri: is travglllng frorn lgft to right at thespeed af s$und
S ff Ssund pr*s$ur€ Lguel il r#fgrsfit*s
.fet flngiil]s at l,##rn
dn wLL4ü
23*TZ*
Fsp ür*up
Heavy Truck
t*nvürs*tian*lSpcech
Lihrary
Sedrasm
Thträsh*ld sf
F*rest
Vuvureln at lrn
Jack hsffirrler at 3.m
Auerägß
Strset Traffic
Susin*ss *ffice
Living Rsoffr
11*
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*heäri*s at äkHe
Psychoacoustlcs LThe ear
ffi*cund?ryäTt
sardrunTf
K
sudittlryfr#rYts
st{
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t*SFk *.*ft
I r The physits sf ths sär
iTh* ürgän of Csrti has tiny hairs tälled hair t€llr:i
iyyrhich rülc iE tn tränsforfn the vibrati*n intcinerve impulses
7r Hearins dailnäges
ürgän nf tcrti tof ä rn*usclin günd üünditifin
The särn* after än *xpüsurrto ä very Inud
iTh* hair tells rän hardly r*genrräte: whenIth*ynre darriäg*d, its finished
xF Froteut yüur rärs !
t'lülst
Er&tr!?*
Psychoacoustlcs 2Percgption of loudness
üutililne
1, - Weber-Fethner Law
7- Absulute Threshold of heäri ng
3 r Equal-lüudness contours
4 - Just-noticeable differences for loudness
5 n Threshsld of hearing and cürnplex sounds
6 r Esti mati ng loudness
1 r Weheil'-Fechiler Lawä3
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= Züüüü P* xl$ ]**., = ZüütX]ü p{ri ,- f{#d
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L;$f,f. # ttütlQu* -+.u:1 i:;iä,i .,,,. L*u* : lüürJ#**ot,.
...as bgtwggn2ü00ü Pa and
?üüüü0 Fa
' .., but the perception is roughly propürti onal tothe dB scale -> That's why the dB is so used !
i
l*r* = St) rJ'ff*",n .$-;; i; u't il,l ,.,.,,.tt"t'.
,.:..., i .,.. :=.:l':""+
There is pet septually äs
rnuch dilfference hetween2üü* Pa and 200üü Fä...
ffiq3 *tlg,lg
ü 4tl{;vl.ä,1
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7 r Absoilute Threshoild of heärt ng
The threshsld sf hearilng is the average level in dB
SPL af the süftest pure toile that humans cän
detect, for eäch frequeilcy
' Note theeffect of age(20,40, soyears) $n thethreshaild
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ü";t]"5ä?5freülil*r?{y *f tesf t*rre {kr*ri
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if*l*{rad
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3 n Equäil-loudness contours
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1 $ü* 1ü*k Freq uency tHt)
5 z Effect uf sgund durätiürlBelnw 0,ä s., the lnnger the sound, the lnuder it willhe perceived
Beyünd 0.2 s., the lüudness is slishtly reduced
5 n lVl äskilngthre$h$ldlf twc tnnäs äre slmultäneously presf,ntsd tn th* sär, theptrt€ptisn of the safteEt tan€ rnäy be rnäsked by the lcudsst
Wdtrf{fffifud trlt'ffirffit rfoiä* W tffrfrffin * kfiäl
Lsudn ess Irnax loudness
1$S
t
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Saund durattün {s}
#,? ü,ä s,-3 ü,4 s,5 #,#
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ü'ä #,s 1 2Fr*qü*ffiä f lrl-le
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tlnsä *,üs üut TS ä$
S n Isti ffitatins lsudnes$Serailse of the frequ*ncy dependenc*, the directrrsasure nf thc s$und pressure level in dß 5f L is nnttünv#ni*nt to esti mate laudnessThus it is ilec*ssäry ta apply ä freqstncy torrscti$nbeforc mräslrring the SpL, that shoilld dep*nd ünloudness r A*weighfinS prüvides ä
rneäsurä in dä4, and isd*signed fcr environ rnenta I
n*ises* {*weighti ng prüvides a
rneäsur* in dBC, and isdesigned fsr lcud nciEes
{a irt raFt, etc... }
E nglis ch- D euts ch Vokab elliste
English DeutschOscillation Schwingung
Root Mean Square (RMS) EffektivwertSound pressure Schalldruck
Sound particle velocity ( =(( pressure gradient u)
Schallschnelle
Sound pressure level (SPL) Scha lld ruckpegelSound wave Schallwelle
Speed of sound Sch a I leeschwi nd igkeit
E nglis ch- D euts ch Vokab elliste
Enelish DeutschEq ua l-loud ness contou rs Ku rven gleicher La utstä rkepegelThreshold of heari ng Hörschwelle
Threshold of pain Schm erzschwelleUltrasound Ultraschalllnfrasound lnfraschallLoudness Lautheit
Masking effect Maskieru ngseffekt