Neurobiological statistics for interpreting problems of musical consonance perception
Jobst P. Fricke

In 1951 Licklider presented a model for pitch perception, based on a periodicity analysis of neural spikes. This process of pitch extraction is similar to an autocorrelation analysis. Langner and Schreiner could prove in 1988 that a periodicity analysis in the auditory organ exists and that the periodicity pitch is neurally represented in the Inferior Colliculus and Cortex. Their dimension is independent of the tonotopical representation and runs in about orthogonal to it. The periodicity of sound signals of consonant intervals could be neuronally proven by means of a periodicity analysis too (Tramo et al. 2001). The periodicity of the acoustic signals however is imperfect in music performance. Intonation deviations, which are a disturbance of the periodicity, are tolerated in the hearing process to a considerable extent. This can be seen particularly in the judgment of consonant intervals. Depending on the musical context, standard deviations of 13 cents for the optimal intonation were measured for the fourth as well as for the fifth. In total the variation was even at 70 cents. For those on this scale experimentally determined hearing tolerances, the statistical processes of neural coding and processing, in particular the neural integration for the autocorrelation, seem to be responsible.