PSYCO104 Lecture Notes - Lecture 6: Middle Ear, Musical Tone, Luminescence

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PSYCH104–Lecture6–SensationandPerception
SignalDetectionTheory:
Introducestheideathatmostofthetimeindividualsarenotcompletelyfixatedon
ataskoraretryingtohearaparticularsound
oOurattentionisdirectedindifferentlocations
oDetectabilitytakesintoaccountthatthereareothermechanismsthatcan
affectstimuli
oFourpossibleoutcomeswhentryingtodetectstimuli:
Hit:actuallydetectthestimuluswhenpresent
Miss:failtodetectstimuluswhenpresent
FalseAlarms:detectstimulusthatisn’tpresent
CorrectRejection:detectthatthereisanabsenceofthestimulus
oDependingontheconsequences,itcanchangethedetectabilityofthe
stimulusforanindividual
Ex.PositioninDetectingEnemyAircraft
Highconsequencesifyoumisstheenemyaircraft(people
willdie)
oWilltendtodirectalotmoreattentiontodetect
stimuliduetohighconsequences
oWillmakemorefalsealarms
SubliminalPerception:
Peopleareabletoperceivethingsbelowtheirconsciousawareness
oEx.Visualreceptorswillfire,butitwillnotproduceenoughactivationthat
thebrainwillprocessit
JamesVicary“EatPopcorn”Experiment
oInsertedsubliminalmessagesintomovies“EatPopcorn”andmomentarily
flashedthewordswithinthedurationofthemovie
Hugeupswingofpeoplebuyingpopcorneventhoughtheydon’t
rememberseeingthemessage
Subliminalperceptionisonlyforshorttermchoices
oChangesinmoodandfeelingsareveryshortlived
SensoryAdaption:
● Thegeneraldeclineinone’ssenseorgansduetorepeatedstimulation
o Ex.SmellyHouse
▪ Neighbour’shousesmellswhenyoufirstwalkintothehouse
● Eventuallyone’ssensereceptorsadapttothisodourand
cannotdetectitafteragiventime
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TheAuditorySystem:Sound
● Soundisthestimulusthatmattersfortheauditorysystem
o Ex.Vibratingobject,guitarstrings,suddenreleaseofair(clapping),
forcedairbeingpushedthrougharestrictivechamber,etc.
▪ Affectedbyloudness,pitchandtimbre
● Amplitude(Loudness)
o Theheightofthesoundwave
▪ Ex.Yellingandwhispering
● Wavelength(Frequency/Pitch)
o Themeasurebetweenonewavepeaktoanotherwavepeak
▪ Ex.Cchord,Dchord,etc.
● Purity(Timbre)
o Thefluctuationsinawave
▪ Howdifferenttheyarefromapuretone(rounded,symmetrical
smoothwave)
● Ex.Cchordonaguitarisdifferentfromapianoandviolin
becausetheyproducedifferenttimbres(havedifferent
patternsofsoundwaves)
HumanHearing:
Frequencyismeasuredinhertz(Hz),thedirectindicationofhowfrequentthe
soundwaveiscycling
oGivenoptimalconditionsahumancanhearsoundsfrom20–20000Hz
oHearingcapacitiesdifferinanimals
Ex.Batscanhearabove20000Hz
Ex.Wecan’thearadogwhistlebecauseit’sbelow/aboveour
rangeofhearing
Amplitude(loudness)ismeasuredindecibels
oThehighertheamplitude,thelouderthesound(notanabsolute
relationship,isaffectedbypitchaswell)
oPainthresholdfortheloudsoundtostartcausingdiscomfort(120
decibels)
Willexperiencephysicalpainandpossibledamagetotheauditory
system
PartsoftheEar:
● ExternalEar
o Mainpurpose:conductthesoundwavefromtheairintoaninternal
structure(eardrum)
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▪ Vibratingairwavesentertheearandwilltraveluntilithitsthe
eardrum
▪ Soundwaveshittheeardrumandthesoundwavescauseitto
vibrate
● MiddleEar(mainlytheossicles)
o Mainpurpose:conductsoundintotheinnerear
▪ Vibratingeardrumtouchestheossiclesandcausesthemtomove
▪ Convertsthesemovementsintomoreforcefulenergyandconnect
totheovalwindow
● InnerEar
o Mainpurpose:transferenceofthemanualvibrationintoafluidvibration
▪ Fluidfilledtunnelwillvibrateastheovalwindowvibrates
● Basilarmembraneholdsallthesensoryreceptorsthat
vibrateinresponsetothefluidvibration 
o Movementleadstoneuralimpulsessenttothe
brainforfurtherprocessing
HearingTheories:
● PlaceTheory
o Dependingonthepitch,itwillvibrateoneparticularareaalongthebasilar
membraneandthenthespecifichaircellsinthatareawillprocessitinto
thebrain
● FrequencyTheory
o Thevibrationwilltransfertothefluidfilledchamberandallofthehaircells
willmoveslightly
▪ Theliquidwillvibratedifferentlydependingonthepitch
● Ex.Dchordmightbefasterliquidvibration,whileAchord
isslowerliquidvibration
● Boththeoriesarecorrect
o Frequencyvibratestheliquiddifferentlydependingonthepitch
▪ Thewavesfromtheliquidvibrationcrestatacertainplace
dependingonthefrequency
● Ex.Cchordmaycausecrestinginonespecificlocation,
andDchordisanotherlocation
▪ Theplaceandfrequencyofthemovementofliquidtranslateinto
perceptionalpitch
AuditoryLocalization:
Havetomoveheadtodetectwherethesoundoriginatedfrom
o Auditorycuesassistourabilitytolocatethesound
SoundIntensity
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