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PSYC 330: Perception. Auditory Processing The Basics. What is sound?. When I speak…… Vibration in vocal cords D isplacement of molecules in the air These displace adjacent molecules Wave travels across the room Enter your ear Cause vibration in your auditory apparatus
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PSYC 330: Perception Auditory Processing The Basics
What is sound? • When I speak…… • Vibration in vocal cords • Displacement of molecules in the air • These displace adjacent molecules • Wave travels across the room • Enter your ear • Cause vibration in your auditory apparatus • You “hear” what I say • Sound dissipates as it moves away from the source • Sounds is REALLY slow 760 mph
A note on notes • Sine wave – pure tone • Complex waves – multiple sine waves • Fourier analysis • - relative height (intensity/amplitude) of each individual frequency in sound (pg 224) • Fundamental – root tone • Harmonics – overtones/halftones
Rock the middle ear, dude!!! Middle ear mechanisms: Malleus, incus, stapes amplify Tensor tympani, stapedius acoustic reflex
Sound transduction MECHANOELECTRICAL transduction (MET) Organ of Corti Stereocilia Tip links http://www.youtube.com/watch?v=lioNIbtFxSY&feature=related
Intensity coding 14,000 hair cells (vs. 100 million rods and cones)
Pitch coding - place http://www.youtube.com/watch?v=dyenMluFaUw Afferent (inner hair cells) and efferent (outer hair cells)
Pitch coding – freq. • Phase locking – auditory nerves produce action potential at specific, consistent point in the phase of the sound wave • Phase locking provides information for temporal coding • Volley principle
Brain or bust! • Auditory nerve cochlear nuclei (medulla) • Superior olive • Inferior colliculi • Medial geniculate nucleus • Auditory cortex • Tonotopic organization • AI, belt cortex, parabelt cortex
PSYCHoAcoustics Thresholds change across frequency
psychoacoustics • Factors influencing thresholds • Species • Frequency • Equal loudness contours • Temporal integration
Hearing loss • Obstructive hearing loss • Conductive hearing loss • Sensorineural hearing loss • Relationship to noise exposure • Relationship to normal aging