A favorite instrument in the orchestra. A familiar voice in a crowd of people. The still of a forest floor and then, suddenly, a snapping twig.
Hearing requires neural processing that sorts and integrates the rich fabric of natural stimuli.
These stimuli include not only elements of pitch or the frequency of sound, but loudness or intensity, harmonics or overtones, phase relationships among wave components of complex sounds, and subtle features of the onset and decay of sounds. Extracting positional cues from differences in timing and intensity helps localize sound and similar processes enhance speech perception in noisy rooms. One fruitful approach in understanding the neural mechanisms of hearing is to identify the connections of individual cell groups or nuclei and the individual cell types within these nuclei. It should not be surprising in light of the complexity of sensory stimuli to find complex brain stem circuitry. Within the brain stem circuitry, multiple orders of nuclei, many containing several cell types, give rise to as many levels of interconnections.