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22 Cards in this Set
- Front
- Back
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how does the middle ear do impedence matching?
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Oval window much smaller than tympanic membrane, same force applied to smaller area greater pressure. Lever action of ossicles.
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What does the middle ear do to filter intense low-frequency sounds?
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The small muscles that connect the ossicles contract reflexively, which reduces the magnitude of the vibrations that reach the oval window. Not quick enough to protect against impulsive sounds.
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What are the characteristics of the base of the basilar membrane? The apex?
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Base: stiff, narrow, high frequencies
Apex: loose, thick, low frequencies |
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Active process
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Outer hair cells amplify basal vibrations slightly above characteristic frequency by expanding and contracting in size in tandem with the vibrations of the basilar membrane. At higher levels, the outer hair cells cannot respond sufficiently, so the gain decreases.
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How are the characteristic frequencies positioned on the basilar membrane?
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Positions of characteristic frequency on the basilar membrane varies with the log of frequency
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In what membrane are the hairs in the Organ of Corti embedded?
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Reissner's membrane
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What is the Organ of Corti?
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Contains rows of hair cells and various supporting cells and nerve endings
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What can you say about the nerve fibers that connect to the inner and outer hair cells?
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Inner hair cells: fibers are afferent (receive information)
Outer hair cells: fibers are efferent (send information from brain stem) -Involved in some kind of feedback |
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How does the transduction of BM vibrations to auditory nerve impulses work?
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Basilar membrane moves sideways relative to the tectorial membrane, the tip links of the stereocilia are stretched, positive ions flow into the stereocilia depolarizing it, causes neuro-transmitters to be released.
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What is two-tone suppression?
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The phenomenon of, when a second tone is added near the characteristic freq on the basilar membrane of a first tone, the response of the basilar membrane at the characteristic freq acutally decreases.
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What is masking in psychophysical experimental techniques?
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Masking occurs whenever the activity produced on the basilar membrane by one sound (the masker) obscures the activity produced by the sound you are trying to hear (the signal).
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Basic masking experimental technique:
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Pure-tone signal fixed at low level; a narrow-band noise or pure tone masker at a certain frequency presented and level raised until the listener can no longer hear the signal.
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Method of limits for loudness perception:
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Descending level of series of tones, wait till can no longer hear; or ascending level of series of tones, wait till can hear; descending series usually gives lower value, ascending series gives higher value
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Adaptive testing for loudness perception:
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Step level up and down around threshold
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Simple reaction time methods:
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Time between onset of a stimulus and the beginning of an overt response to it
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What is the critical band in masking experiments?
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When the masker bandwidth is larger than the critical bandwidth around the signal tone, additional increases in the masker bandwidth have not additional suppression effects.
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Notched noise method
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Masker occurs in the bandwidth on both sides of a noise-free notch. As the notch is narrow, more noise passes into the auditory filter and you can suppress the signal using a smaller level of noise.
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What is the equivalent rectangular bandwidth of a filter? (ERB)
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The ERB of a filter is the bandwidth of a rectangular filter with the same peak output and the same area as the filter.
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dynamic range of a system
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the range of levels over which the system operates to a certain standard of performance
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what is the dynamic range of hearing for the mid-frequency region?
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about 120dB, decreases at low and high frequencies
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How is the phon scale derived?
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Loudness level in phons taken as the level (in dB SPL) of a 1 kHz tone to which it is equal in loudness
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What does loudness depend on besides level?
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Depends also on bandwidth and duration: up to a few hundred milliseconds, the longer the sound the louder it appears; most likely due to more samples, more sure of sound
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