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Listserve Members,
An implied or stated goal of some hearing aid processing strategies is to
compensate for the lost compressive function of the cochlea resulting from
sensorineural hearing loss. I am in the process of writing a brief paper (as
part of my doctoral coursework) discussing the ability of current devices to
actually do this and the pros and cons of even attempting to do so. Initially, I
am trying to describe the "compression parameters" of the normal cochlea. I have
found substantial physiologic work in various animals suggesting linear function
below an initial "compression threshold" of about 20-40 dB SPL and some
psychophysical work in humans suggesting an initial "compression
threshold" of 20 dB SPL or less. For midlevel inputs (40-90 to 110 dB SPL
or so) a compression ratio of about 5:1 (7:1 to 3:1) has been suggested. For
high levels (above 90 to 110 dB) some research suggests linear functioning but I
am unclear on which references support this idea. I have not found any
references that discuss potential "time constants" for the normal cochlea. I
believe some physiologic work on outer hair cells has suggested they can
function essentially instantaneously.
In short, I am interested in references that may discuss the compressive
nonlinearity of the cochlea in terms of "compression characteristics". In
specific, references for a second high level compression threshold and a
discussion of "cochlear time constants". Any thoughts or ideas are
appreciated.
Ben Hornsby
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