Re: Eckard Blumschein: Perception of irregular short pulses (Jont Allen )

Subject: Re: Eckard Blumschein: Perception of irregular short pulses
From:    Jont Allen  <jba(at)RESEARCH.ATT.COM>
Date:    Sun, 5 Oct 1997 00:39:23 -0400

Dan Ellis wrote: > > Dear List - > > Eckard Blumschein of Magdeburg sent me the enclosed message for your > consideration. It describes some intriguing problems of investigating > the sound of arc-welding (!) > > DAn. > > ------- Forwarded Message > Date: Thu, 02 Oct 1997 17:40:49 +0200 > From: Eckard Blumschein <blumschein(at)E-Technik.Uni-Magdeburg.DE> .... > > I recently realized a most convincing theory by Jont Allen explaining > dynamic range of hearing. He says, stiffness of basilar membrane is slowly > adapted to intensity of excitation via changing length of outer hair cells. > My question is, how fast does this active feedback ease and rebuilt tension > of BM? The response of the hair cell length/force has been shown to follow the voltage in the cell, which is limited by its membrane time constant. Experiments have shown this time constant to be about 1 to 1.2 ms. Thus, the release time could be very fast, but the recover time would be 1.2 ms. > > Our recording system adapted itself to maximum of sound pressure. As a > consequence no peaks were cut off. If, however, a simple sound card was used > for recording the narrow spiked signal, then inevitably almost all spikes > were rigorously clipped to the same length because the sound card adapted > very slowly to mean value of sound signal. You should get a better ADC. One that has no AGC or is more linear. > > Certainly, human outer hair cells can not respond in time to an incoming > needle of sound. Corollary: Sudden sound pulse might hit basilar membrane > before it is adapted by eased tension. The loud crack has an other, a > physically plausible reason, too. Here it is worth to be noticed merely > because it might give a deeper insight in how single bangs, cracks, and > clicks are perceived. There is significant dispersion by the BM before the signal reaches the OHC. There has been quite a bit of work on impulsive noise by the Army. It has been published in JASA. > > Sincerely, > Eckard Blumschein, 1997, Oct. 1 > > Otto of Guericke University Magdeburg > Dept. of Electrical Engineering > IELE > PSF 4120 > D-39016 Magdeburg > > Phone: + 49 391 67 12403 Fax: + 49 391 67 12408 > > blumschein(at) > > ------- End of Forwarded Message Jont -- ==> NOTE NEW ADDRESS AND PHONE NUMBER: Jont B. Allen, Room B009; 973(or 201)/360-8545voice, x8092fax;; AT&T Labs-Research 180 Park AV; PO Box 971; Florham Park NJ 07932-0971

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Electrical Engineering Dept., Columbia University