acoustics unplugged

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  • 1. RebeccaReichMay242011
  • 2. WhoamI? h Audio/Acousticsaroundtheclock d d h l k
  • 3. 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 B.Eng,electrical,MinorArts NRCWomeninEngineeringandSciencescholarship g g p classroomandconcerthallacoustics S.M.,MediaArtsandSciences Cochlearimplants hl l howdotheysoundwhenmusicplaysthroughthem?
  • 4. 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Programming1sand0s Programmingusersoftware Customertechnical support
  • 5. 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 OneyearinCopenhagen,DK Customertechnicalsupport
  • 6. 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Customertechnicalsupport(fivemonths) C h i l (fi h ) Manager,customertechnicalsupportteam China,Japan,Canada
  • 7. 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Flexible Peoplejobwww.mitacs.ca Learnnewstuff!
  • 8. $7500industry 75 y $15 000 $7500Mitacs/FQRNT $10 000 $5000min for student flexible $36000industry $80 000 $44000Mitacs/FQRNT $10 000 $10 000 $10 000 $20 000 $10 000 $10 000 $10 000 flexible internships
  • 9. LetsgetstartedLetsgetstarted
  • 10. Soundisaformofenergy(likeelectricityor f f light) Soundismadewhenairmoleculesvibrate d d h l l b andmoveinapatternwaves AnimationcourtesyofDr.DanRussell,KetteringUniversity
  • 11. Particlemotionisafunctionofspace (displacement,amplitude) andtime
  • 12. Longitudinal wave: particlemotionisparallel tomotionofdisturbance createdbymovingobject Wavecausesareasofcompression(high pressure)andrarefaction(lowpressure).We ) d f i (l ) W callthisPRESSUREwaves
  • 13. c=343m/s(air,20oC) weINTERPRETsoundwaves
  • 14. Frequency: Fhowoften theparticlesaremovingbackandforth: #ofcompletebackandforthvibrations p ofaparticleofthemedium Hertz: perunitoftime #cyclespersecond 20Hz 20000Hz H H Sensationoffrequency=pitch
  • 15. Greateramplitudeofdisturbancecauses G li d fdi b greaterdisplacement(amplitude)ofparticles Moreamplitude moreenergy Intensity=power/area(Watts/m2) Moveawayfromsound,intensitydecreases (inversesquare) Humanscandetectaslowas1*1012 W/m2,, andashighas1billiontimesthis! Duetolargerange:dB 1*1012 W/m2=0dB d
  • 16. sleep work work wake play
  • 17. Youralarmclockradio:fastfacts f f06:00 WhydoesBostonAcousticssoundbetter thanAccurian?
  • 18. Lookingatanaverageoverawindowoftime
  • 19. Whydoeseveryonesoundgoodsinginginthe Wh d d d i i i th shower?06:15 5 ACOUSTICS:studyofwavesinamedium Direct,Reflected,Refracted,Absorbed fl d f d b b d
  • 20. Hardsurfaces f littlesoundabsorbed(ceramictile) manyreflections reverberation ~50msisthresholdfor i th h ldf hearingecho
  • 21. Smallspace accumulationofreflections increasesvolume yousoundmorepowerful! Resonantcavity Showerstalldimensions causestandingwavesat d lowfrequencies;vocalsin thisrangewillbeboosted
  • 22. Carstereoacoustics08:00 deadsoundenvironment,dependsonmaterials (leathervs.upholstry) transitory(windowsopenvs.closed) loud:ridingthevolumeknob
  • 23. Singlebandcompressor,loudbassinformation l b d l db f modulatesgainoftheentireaudiosignal suboptimalmaximumperceivedloudness&gain pumping
  • 24. ListeningtoiPod [Portnuff]listeningtoearbuds for90minutes/dayat 80%volumeisprobablysafeforlongtermhearing (softerisbetter:youcansafelytuneinat70% volumeforabout4hoursaday.) volumeforabout4hoursaday )~oneinfiveteenagershadsomekindofhearinglossin2005 2006,upfrom15%ofteenagersinthelate1980sand20052006,upfrom15%ofteenagersinthelate1980sandearly90s,accordingtoastudyofnearly5,000peopleage12to19publishedintheJournaloftheAmericanMedicalAssociation.
  • 25. Themaximumexposuretimeforunprotected Th i ti f t t d earsperdayat90dBis8hours. Forevery5dBincreaseinvolume themaximum Forevery5dBincreaseinvolume,themaximum exposuretimeiscutinhalf. 95 95dB=4hours 4 100dB=2hours 110dB=30minutes 120dB=7.5minutes Appleset100dBlimitinEurope,still115dBin USA
  • 26. Dynamiccompressionarealityofmodern f musicrecordings(louderisbetter) Causeslistenerfatigue l f
  • 27. 08:45 45 Ingeneral,noiselevelsabove4550dB(A)tendtobe I l i l l b dB(A) d b disturbing SpeechIntelligibilityIndex(SII):howwellspeechcanbe understoodinthe