Subject: Pitch perception break-point at 170 Hz From: Eckard Blumschein <Eckard.Blumschein(at)E-TECHNIK.UNI-MAGDEBURG.DE> Date: Thu, 24 Aug 2000 13:32:13 +0200Dear Martin Braun, After Jont Allen twice objected against your idea of damping basilar membrane, I am just about explaining the dynamic range as roughly tree times 40 dB. You are reminding me of a perhaps even more important matter. Well, I am convinced you are right, and I already tried to provide an explanation to this phenomenon, puzzling so many researcher. Maybe, my posting #259 (07/13 this year) was somewhat misleading and partially incorrect. However, I go on sticking to the following: Neurons preferably detect coincidence of lowest order. Tonal perception might be based on zero order ICIs (intra channel coincidence). I got aware that atonal perception across all CFs starts to become amenable as soon as period exceeds refractory time. In that case the normally dominating intervals are presumably getting increasingly corrupted by shorter ones of random length. The brain may switch to the alternative information bypassing the tonotopy. This guess of mine seems to backed by a strange sudden change of laterality after a while, similar to some auditory illusions by Diana Deutsch and according to experiments by Houtsma. What about exactly 170 Hz, those who were dealing with related phenomena are facing uncertainties of psychoacoustic measurement. A figure by Warren shows the transition for periodic signals with alternating polarity between 100 and 200 Hz. If I remember correctly, Patterson gave a limit for perception of phase up to 400 or 500 Hz (in good agreement to rarefaction time). The latter case marks the possibility of what some people call temporal perception. Values below 200 Hz rather correspond to the change in overall assessment. You might wonder why I am reluctant to distinguish between temporal perception below that fairly gradual limit and spectral perception above it. I just would like to express my heretical opinion that the tonal perception is based on a temporal mechanism, too. Yours sincerely, Eckard Blumschein