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PSYC 330: Perception

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

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  1. PSYC 330: Perception Auditory Processing The Basics

  2. 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

  3. Qualities of sound

  4. 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 247) • Fundamental – root tone • Harmonics – overtones/halftones

  5. Harmonics

  6. Fourier analysis

  7. The hardware

  8. Rock the middle ear, dude!!! Middle ear mechanisms: Malleus, incus, stapes  amplify Tensor tympani, stapedius  acoustic reflex

  9. the cochlea

  10. http://www.youtube.com/watch?v=PeTriGTENoc

  11. Sound transduction MECHANOELECTRICAL transduction (MET) Organ of Corti Stereocilia Tip links MET is FAST and EXTREMELY SENSITIVE

  12. Intensity coding 14,000 hair cells (vs. 100 million rods and cones) Sound intensity Shear intensity  Greater stretching more NT

  13. Pitch coding - place http://www.youtube.com/watch?v=dyenMluFaUw Afferent (inner hair cells) and efferent (outer hair cells)

  14. Place theory • Why do different parts of the basilar membrane get displaced differently relative to frequency? • Base is stiffer  more reaction to higher frequency • Apex is wider and more flexible  more reaction to lower frequency • Neurons that make up the auditory nerve tonotopic voila! Perception of pitch

  15. 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

  16. Phase locking

  17. Brain or bust! • Auditory nerve  cochlear nuclei (medulla) • Superior olive • Inferior colliculi • Medial geniculate nucleus • Auditory cortex • Tonotopic organization • AI, belt cortex, parabelt cortex

  18. PSYCHoAcoustics Thresholds change across frequency

  19. psychoacoustics • Factors influencing thresholds • Species • Frequency • Equal loudness contours • Temporal integration

  20. Hearing loss • Conductive hearing loss • Sensorineural hearing loss • Relationship to noise exposure • Relationship to normal aging

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