Subject: Re: pitch neurons From: Martin Braun <nombraun(at)POST.NETLINK.SE> Date: Thu, 10 Oct 2002 11:33:23 +0200Israel Nelken wrote: > When you > say 'pitch neuron', I understand that you are looking for a neuron that > should respond to pitch irrespective of the underlying physical > structure of the stimulus - missing fundamental or not, iterated ripple > noise, high-pass filtered click trains, binaural or monaural, and so on > and so forth. Dennis Phillips wrote: > Pitch percepts arise from a host of very diverse stimulus configurations. Dear Eli, Dennis, and List, I suggest we should never forget that this "host of very diverse stimulus configurations" is a lab artefact. No ears or brains are in any way adapted to "iterated ripple noise, or high-pass filtered click trains". They are not even adapted to "pure tones". These things do not occur outside the lab. Outside the lab all sound is broad-band noise with varying amounts of periodic components. If these are strong enough, we hear pitch, otherwise we don't. The advantage of detecting a pitch is that it helps the animal to identify and follow a sound source. In order to do this, the animal needs ONE pitch detector, not several. More than one would only lead to a more diffuse pitch. It is obvious that complex sound with only unresolved harmonics produces a pitch perception. But such sound is non-existent in a natural environment, and this pitch percept is weaker and slower than that caused by natural sound with resolved harmonics. Experiments with unnatural periodic sound are useful to test the limits of certain systems, but they never justify the conclusion that we have two or more pitch detectors. It would be more plausible to say that, upon artificial periodic sound, non-pitch systems can deliver information to the pitch system as a by-product. Martin ------------------------------------------- Martin Braun Neuroscience of Music S-671 95 Klässbol Sweden e-mail: nombraun(at)post.netlink.se web site: http://hem.netlink.se/~sbe29751/home.htm ------------------------------------------- On the evolution of a fact in science: Stage 1 .......................... "Totally absurd stuff." Stage 2 .......................... "Interesting, but queer." Stage 3 .......................... "Correct, but unimportant." Stage 4 .......................... "I have always said this." [John BS Haldane (1892 - 1964), biologist]