In guinea pigs, the constant iontophoretic release of transmitter agonists in the synaptic cleft of inner hair cells (IHC) triggers chemically an irregular and bursting mode of spiking discharge, subsynaptically recorded in the afferent dendrites. The tendency to form spike clusters appears to be independent of the quality and quantity of the used test substances, the excitatory amino acids N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4- isoxazole-propionic acid (AMPA). The recorded spike trains show a remarkable stability of the calculated individual box-counting dimension characterizing the bursting behaviour as a fractal random point process. The fractal kinetics seems to reflect molecular instabilities of cochlear afferent glutamate receptors, determining the mode of the signal transmission in the auditory periphery.