Subject: A Compression System within the Cochlea From: Ben Hornsby <ben.hornsby(at)VANDERBILT.EDU> Date: Tue, 28 Mar 2000 08:21:05 -0600This is a multi-part message in MIME format. ------=_NextPart_000_002F_01BF988E.8FD45AE0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable 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.=20 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 ------=_NextPart_000_002F_01BF988E.8FD45AE0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META content=3D"text/html; charset=3Diso-8859-1" = http-equiv=3DContent-Type> <META content=3D"MSHTML 5.00.2314.1000" name=3DGENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=3D#ffffff> <DIV>Listserve Members,</DIV> <DIV> </DIV> <DIV>An implied or stated goal of some hearing aid processing strategies = is to=20 compensate for the lost compressive function of the = cochlea resulting from=20 sensorineural hearing loss. I am in the process of writing a brief paper = (as=20 part of my doctoral coursework) discussing the ability of current = devices to=20 actually do this and the pros and cons of even attempting to do so. = Initially, I=20 am trying to describe the "compression parameters" of the normal = cochlea. I have=20 found substantial physiologic work in various animals suggesting linear = function=20 below an initial "compression threshold" of about 20-40 dB SPL and some = psychophysical work in humans suggesting an initial "compression=20 threshold" of 20 dB SPL or less. For midlevel inputs (40-90 to 110 = dB SPL=20 or so) a compression ratio of about 5:1 (7:1 to 3:1) has been suggested. = For=20 high levels (above 90 to 110 dB) some research suggests linear = functioning but I=20 am unclear on which references support this idea. I have not found any=20 references that discuss potential "time constants" for the normal = cochlea. I=20 believe some physiologic work on outer hair cells has suggested they can = function essentially instantaneously. </DIV> <DIV>In short, I am interested in references that may discuss the = compressive=20 nonlinearity of the cochlea in terms of "compression characteristics". = In=20 specific, references for a second high level compression threshold and a = discussion of "cochlear time constants". Any thoughts or ideas are=20 appreciated.</DIV> <DIV> </DIV> <DIV>Ben Hornsby</DIV></BODY></HTML> ------=_NextPart_000_002F_01BF988E.8FD45AE0--