Gliding rippled spectrum discrimination: Ripple density and gliding velocity limits

Rippled noise is a productive model of natural signals with complex spectrum patterns. It was used as a test signal to measure spectrum-pattern resolution both in normal-hearing listeners and in hearing-impaired listeners and users of cochlear implants. However, a variety of natural auditory signals feature combined spectro-temporal patterns. These signals may be modeled by rippled noise with “gliding” ripples. In the present study, ripple gliding velocity limits as a function of ripple density were measured in normal-hearing listeners. The highest gliding velocity (expressed in oct/s or ripples/s) at which the gliding ripple pattern could be distinguished from a non-rippled noise was determined. The ripple gliding velocity limit decreased from approximately 400-500 ripple/s at a ripple density of 1 ripple/oct to approximately 50 ripple/s at a ripple density of 7 ripple/oct. The data are explained by a model based on a combine action of the excitation-pattern and temporal-processing mechanisms.