Subject: Pitch in a non-animate world From: "John K. Bates" <jkbates(at)COMPUTER.NET> Date: Thu, 3 Mar 2005 17:18:09 -0500Dear list, The discussion on the interrelationships of animals with the sounds of their natural environments has interesting implications. I think it should be pursued. Here's a simplistic version of my thinking. Animals evolved "ears" as a sensor to enhance survival. To do this each species has evolved auditory processing technology to handle problems peculiar to its environmental niche. Each niche imposes auditory requirements and constraints that are increasingly demanding in proportion to each evolutionary level. As Al has pointed out, animal-free environments have essentially no periodic or tonal sources. Periodic sounds have appeared as a result of the evolution of animals. To an animal, tonal or impulsive events in the natural environment have usually represented significant threats to survival. Tonal/periodic sounds as well as impulsive sounds therefore represent animals that are either threats or benefits. Thus, ears, especially in mammals, have evolved technology that can extract meaning from both tonal and atonal sounds, not to mention the fact that the sounds are generally intermixed...the well-known acoustic scene. To accomplish all this the ear's processing methods, regardless of species, have responded successfully to conflicting fundamental requirements in time and frequency. For example, temporal requirements for locating sounds impose extremely fast response times that are incompatible with the frequency domain...And then there's the problem of unravelling mixed spectra in informational masking. The question is: How have animals been able to resolve this conflict? One should ask whether the cochlea really does a spectral analysis or whether some kind of an alternative processor is subtly in place. Regards, John Bates