Subject: Basilar-Tectorial Membrane - Harmonic Analysis? From: "Richard J. Fabbri" <fabbri(at)NETAXIS.COM> Date: Wed, 21 Oct 1998 04:34:04 -0400Dear List, As stated in an earlier posting ... - "What if Source separation produced Source data of a form that present analysis could not handle? What if Source separation transforms Binaural data sets into Source data sets and ... those Source data sets were inconsistent with Fourier analysis? - Are we ready for a paradigm shift?" On this line of questioning, I would like to open a discussion concerning a different view of the Basilar-Tectorial (BT) membrane. BT resonant response occurs at a given time and actually represents the largest energy component AT THAT TIME ... ... Flannagan says it well in "Speech Analysis, Synthesis and Perception", 2nd, Expanded Edition, bottom p149 thru top 150: "For most speech signals, ... the [BT analysis] provides better temporal resolution than spectral resolution. Generally, the only harmonic component resolved mechanically is the fundamental frequency [highest energy] of voiced segments." Thus, it is more accurate to think of the Place Theory as producing a (time) sequence of resonant events. However, a true Fourier analysis produces a SET of Frequency estimates (and a SET of associated Phases) at a resonant resolution related to the sampled-time-interval. A "filterbank" is a (parallel) SET of filters. The BT structure resonants at only ONE place at only ONE time, i.e., the "filterbank" analogy is seriously lacking the ability to produce a SET of resonances. If we agree (?) that the BT is not a "filterbank" then, of what Fourier value is this single, temporally resonant, BT filter? The Place Theory predicts particular resonances are transduced by particular groups of IHC's. But, I've never "heard" discrete, sequential, sine wave speech, i.e., the ONLY form of speech that could be *spectrally* detected by a temporal, single-resonance BT detector! Old 300 baud modems employed this kind of communication. But, don't be too concerned because BT resonances are NOT the important feature provided by the BT IHC's ... ... HALFwave transduced time cues are the basic BT data. But, much more, a whole new form of analysis based on Chaos (multidimensional geometry) and Self-Organized Neural Maps solves the Cocktail Party Effect and provides the data streams produced by separated, acoustic sources. Regards, Rich McGill is running a new version of LISTSERV (1.8d on Windows NT). Information is available on the WEB at http://www.mcgill.ca/cc/listserv