Spatial periodicity in the cochlea: the result of interaction of spontaneous emissions?

In this study the results of simulations with a nonlinear macromechanical model of the human cochlea are presented. In this model it is possible to investigate the interactions between large numbers of spontaneous emissions. The focus of this study is on the effect of a local maximum in emission strength on its direct surroundings. The suppression that such an emitter causes depends on the distance between suppressor and suppressee in a strongly nonmonotonic manner. This nonmonotonicity leads to natural minimal distances between emission frequencies, without additional assumptions about the mechanics of the cochlea. The origin of this nonmonotonicity in the suppression lies in reflection of the generated energy at the stapes. The fact that these minimum distances correspond to distances observed between measured SOAE frequencies in adults, but not in newborns, suggests that the nonmonotonicity may play a role in the development of the cochlea in the early years of childhood.