Die mit Mikroelektroden ableitbare Reaktion einzelner Elemente des colliculus inferior und des corpus geniculatum mediale auf akustische Reize verschiedener Form und verschiedener Intensit�t

[The phenomenon of hearing: an interdisciplinary discussion. II]

This part of the paper deals with the neurophysiological background of speech analysis and hearing of music. Single vowel- and consonant-detector cells could be clearly separated at the colliculus and geniculate level (Kallert, Keidel). Musical stimulation is decoded at three levels: hair cells, geniculate, and auditory cortex. Human cortical evoked potentials represent rhythm, consonance, and (as DC-shift) the emotional content of music. Marked harmonics, even of single hair-cell vibrations and in single units of medial geniculate in combination with clock-cell networks, are the physiological basis of "harmony" in music. Dissonant stimuli are detectable at the cortical level in man (Finkenzeller, Keidel).

[The phenomenon of hearing: an interdisciplinary discourse. I]

For the last century hearing has been considered a purely passive process. G. S. Ohm's and H. v. Helmholtz's resonance theory of hearing was widely accepted until Wien's fundamental objection led to G. v. Békésy's and O. F. Ranke's travelling wave theory, the hydrodynamics of the inner ear that distributes the frequencies along the basilar membrane, which acts as the "first filter". Seebeck, Licklider, Schouten, and deBoer emphasized also the time domain and developed the concept of periodicity hearing and the "residue phenomenon". However, it was not until the concept of the "cochlear amplifier" and "active hearing" with energy generation during the transduction process within the ear itself was introduced that the "second filter" could be understood. Kemp's echo was the key to this revolutionary step in the theory of hearing.