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Lecture

PSY280H1 Lecture Notes - Eardrum, Hair Cell, Spiral Ganglion


Department
Psychology
Course Code
PSY280H1
Professor
saverino

Page:
of 11
PSY280 JULY 26, 2012
THE EAR
Perceived through the ear
Video of ind 29 deaf all of life, and got cochlear implant
And her rxn
If lose vision or hearing which one,
Physical stim is soundwaves
Structures of the ear to perceive sound
Per process
- Similar to vision 3 steps
- Stim is sound eaves popageated through space in a medium
- In photore done in inner hair cells
- Hearing get sent to area that process auditory stimulation
- Localaixtion and identification allow for interaction
Sound
- Some medium allows vibrations to pass
- Outerspace is a vacuum no sound
- Changes in mechanical pressure
- Flick string air compress forward increase air pressure and as comes back rarificaion sucks it
back tihtly then refraction and then compress
- Compression increase in pressure and rar is decrease relative to pressure
Sound wave
- Single sound pure tone not that many in env are artificial
- Compression and rare, compression is peak and rare is trough
- Difference in peak is wv
- One cycle is maximum pressure back to min to max
- Max min then max
Contd
- 4 dimensions
- Same as visial wv
Contd
- Number per second
- High freq then pitch
- Within one second more
- Hear 2- to 20000 hz
- Hertz is unit of freq
- 1 hert is one cycle per second
Amo
- Loudness
- Size of pressure change
- Greater compression high ampl
- In decibels, one tenth of bel of Alexander grand bell bc investigated sound wave,
- Min .0002 and 280, change per area
Pressure
- Convert to decibels
- Use log scale
- P is sound pressure or ampl
- 50/ refrence pressure, pressure of air at baseline no wave propagating through it
- Not increase not 1 to 1
- Db increase less then air pressure
- Slower rate of increase
Sound wave
- Phase is comp and rar whether at peak or dip
- Phase as degrees
- At zero up peak is 90 then base is 180 half circle
- Length of 180 varies across different sound sources
Contd
- Can be added to make different sound
- Pure tones good but not in environment
- Complex sounds add pure tones
- Similar phase, same peaks as other swave both at 180 then addition
- Amp is added
- Overlap add together 20 and 20 is 40 decibels
- Out of phase full 180 peaks when other dips
- Increase and dec subtract out flat line
- Different waves parts overlap and not one top 2 bottom some added and some subtracted
Harmonics
- Everyday sounds more complex
- Many harmonics
- Harmonics
- Each harmonic one frequency
- Each would be multiple of 200 hertz second 400 and third 600
- Complex sounds
- 4 harmonics get four peaks or repetition beat of 4 then start over
- Harmonic stays the same
- Related to pitch
Contd
- Remove one harmonic
- Fund the first one, 4 beats and repea
- No pitch difference bc every 200 hertz
- Difference in timbre quality of sound
- Same tone same frequwncy same pitch but different instrument
- Sounds the same peaks and dips different quality of sound same tone dif in quality
Loundness
- High amp more and low amp less intense
- Freq is pitch
Perc
- Amp loudness depends on frequency
- Freq 1000 to 5000 leas amount of intensity, is speech perception
- So most atune to it
- Higher and lower more intensity to perciee it
- Black is lines detect difference 1000 hertz at 30 to and compare what would be detected same
degree
- To loud in sound 120 dc not matter frequency levels off, freq not much of impact lower freq
matters
- Beneath inaudible
Contd
- Freq influence loud but also duration
- 10 db for 10 sec and 5 db for 20 sec