Abstract
This paper discusses the effects of masking noise on minimum audible pressure.As the increase of masking noise level, the difference between threshold measured by ascending sequence and that measured by descending sequence becomes larger and the perception to pure tone gets dispersive.When the loudness of pure tone is soft at the high level of masking noise, the histogram of the degree of the judgment to pure tone has bimodality.As a result, it is clarified that such a discontinuous change of the perception to pure tone can be modeled by means of the stochastic cusp catastrophe model.
