COMD2081, Domma, Test 2

COMD2081, Domma, Test 2 - 9/27/07 Hearing and Its Disorders...

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9/27/07 Hearing and Its Disorders Acoustics o Study of sound as a physical event Psychoacoustics o Study of sound as a psychological event What is Sound? o Source is a mechanical vibration of an object o Vibrations create waves of disturbance o Waves then travel through a medium o Medium must be elastic to carry sound o To be called a sound the disturbance must be audible Sound : The audible disturbance of a medium produced by a source Sound  Source o Vibration of elastic object o Frequency: number of cycles per second o Pure tone: single frequency tone o Complex tone:  two or more different frequencies o Periodic:  pattern that repeats itself (pure tone) o Aperiodic:  no repetitive pattern (noise) Sound Waves: o Compression:  molecules are close together o Rarefaction:  molecules are spread apart Human Audibility
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o 20 Hz to 20,000 Hz (mosquito ringtone. . google it!) o Dogs- 40,000Hz -60,000 Hz Pitch vs. Frequency o Pitch:  perceptual correlate of frequency;  how you perceive it o Pitch aka Frequency Loudness vs. Amplitude o Amplitude:  extent of molecule displacement in to and fro motion o Loudness:  perceptual correlate of amplitude o Amplitude and pitch aren’t related but can be Decibel (dB) o Measure of sound pressure (loudness or intensity) o Linear scale is too large to measure o Use logarithmic scale o 0 to 130 dB (human ear) o Conversational  Speech:  50-70 dB o Live Rock Concerts:  115- 120 dB o Pain:  140 dB (if you have hearing loss, dB is a lower number) o dBHL:  Hearing level Normal Auditory Development o Fetus o New Born:  get startled by loud sounds (moro reflex) o Infant:  turns head to sound 10/2/07
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Sound Conduction: o Air conduction -Entire system o Bone conduction (medal head band with plastic vibrating disc on mastoid to test inner ear) -Inner ear -Taped voice -Talking- air and bone conduction vs. tape recording- air conduction o Audiology -Study of hearing, its disorders, and the measurement and management of those disorders o Audiologist -Expert in hearing and its disorders o Audiometer -Instrument used to test hearing Assessment: Pure Tone Audiology o Threshold (softest level that the patient can hear of the tone at least 50% of the time) o Air conduction (testing with headphones) -testing entire system; sounds traveling through air o Bone conduction -only testing inner ear Assessment: Acoustic Immittance o Tests the middle ear function o Acoustic Reflex 
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-Measures response of muscles in middle ear in response to a loud sound o Tympanometry -Measures movement of the eardrum and middle ear pressure Assessment: Electrophysiological Tests o Auditory Brainstem Response -Measures brain activity in response to sound
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This note was uploaded on 04/29/2008 for the course COMD 2081 taught by Professor Domma during the Spring '08 term at LSU.

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COMD2081, Domma, Test 2 - 9/27/07 Hearing and Its Disorders...

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