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PSYO 1011 Lecture Notes - Lecture 4: Outer Ear, Inner Ear, Middle EarPremium

2 pages45 viewsFall 2018

Course Code
PSYO 1011
Leanne Stevens,Shelley Adamo,Kevin Duffy,Jennifer Stamp

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PSYO 1011 Lecture Notes Oct. 18th, 2018
Hearing: The Auditory System
The auditory system is designed to detect sound waves
Air molecules are required to generate sound waves
Compression and refraction combined produces sound waves
o The number of cycles per second
o Peak to peak
o 1 cycle per second = 1 Hz
o Perceived as pitch (codes pitch perception)
o Distance between the peak and the troth
o Encodes amplitude as loudness
o Unit of loudness is called decibels (dB)
o 0 dB = smallest detectable sound
o 10 dB = 10x
o 20 dB = 100x
o 30 dB = 1000x
o 60 dB - conversation
o 120 dB - concert
o 160 dB - immediate damage to auditory system
Sound waves
o Two simple waves combined make a complex wave
o Spectrum graph - x axis (Hz) and y axis (module mV)
Humans can detect all frequencies between 20Hz and 20,000Hz
Young adult -> 20 Hz - 20,000 Hz
Older adult -> 20 Hz - 15,000 Hz
Most sensitive -> 2,000 - 5,000 Hz
Anatomy of the Ear
Outer ear
o Pinna -> funnels sound waves
o External meatus (ear canal)
o Eardrum (tympanic membrane)
Middle ear
o 3 bones (ossicles)
Inner ear
o Cochlea (Latin for snail)
Loudness and Pitch Perception
o Coded by (1) the degree of hair cell bending, and by (2) neurons that are activated only after
a threshold level of hair cell bending
o Frequency theory (phase locking) states that the frequency of nerve impulses sent to the
brain matches the frequency of the sound
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