PSYCHOLOGY 6014



THE AUDITORY SYSTEM519493593980Cliché: If a tree falls in the forest, and no one is there, does it make a sound…?00Cliché: If a tree falls in the forest, and no one is there, does it make a sound…?1. Physical Stimulus: SoundVibration of an object leads to compressions & rarefactions of the material in the objectThis can be transferred and transmitted to other media (like air)4280535508000Can describe the sound in terms of physical properties:Frequency (Hertz, HZ)Wavelength (meters, m)4280535135255Pthreshold = 0.0002 dynes/cm2=20 ?Pa = SPL00Pthreshold = 0.0002 dynes/cm2=20 ?Pa = SPLAmplitude (decibels, dB)49663358737606 dB change means a doubling in intensity006 dB change means a doubling in intensityComplexity (spectrum, etc.)2. Perceptual Attributes (Psychological experience of physical attributes) Frequency PitchAmplitude LoudnessComplexity“richness”“brightness”right9525DEMO: Spectral Components00DEMO: Spectral Components“timbre”Key point: there is a physical stimulus, with physical attributes that are essentially incontrovertible; there are also perceived, psychological descriptions of the stimulus that can change for a number of reasonsright40005How is this like time perception?00How is this like time perception?Both top-down and bottom-up processes at work in affecting perception of sounds3. Anatomy of the Auditory SystemOuter ear, middle ear, inner ear/cochlea, auditory nerve, auditory pathway, auditory cortex348043510795000Outer earPinna (“ears”)External auditory canal336613573914000Eardrum – tympanic membraneMiddle earOssicles (malleus, incus, stapes)Acoustic reflexInner ear (cochlea)Cochlea (anatomy only, today)-29146569215000450913538608000376682016954500Auditory neural pathway Cochlear nerveCentral auditory pathway (up to auditory cortex)Acronym Mnemonic:5309235-59055With only 3500 inner hair cells, how can we determine all the complex sounds?00With only 3500 inner hair cells, how can we determine all the complex sounds?4. Functioning of the cochleaBasic transduction process473773515113000RATE theory4966335170624500405193533464500PLACE theory (Traveling wave along basilar membrane)Combination4737735-28765500Hair cell functioning4509135101282500Inner hair cellsOuter hair cells“Characteristic frequency” of auditory nerve fiber5. Auditory Cortex5617210-40195500Pathway (recall from previous lecture)Primary Auditory Receiving Area (A1)“Core” = A1 + some surrounding areas496633516764000Secondary auditory cortexAuditory association cortex4737735133604000Tonotopic mapColumnar arrangementPlasticity of perception(See next page)1765935-744855001880235470789000 ................
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