Physiology of the Cochlear Nuclei

Most of our knowledge concerning auditory signal processing is based on the response of auditory nerve fibers. To a certain degree, these peripheral fibers function as bandpass filters, relaying the spectral analysis performed in the cochlea to higher nervous centers. However, the auditory coding of acoustic signals involves far more than just frequency analysis. For example, the sensation of low pitch associated with musical melody and speech prosody appears to be relatively independent of spectral analysis since different portions of the spectrum can give rise to this percept. The ability to focus upon a single signal among many concurrently presented also involves mechanisms which lie beyond the reach of the auditory periphery. Thus, many properties of acoustic signals are processed in parallel, providing information not only concerning the spectrum per se, but about certain “ecological” aspects of the signal source, including its location, approximate size and trajectory.