David M. Green
Psychoacoust. Lab., Psychol. Dept., Univ. of Florida, Gainesville, FL 32611-2065
This is a review of current theories and recent experimental data on how human listeners detect changes in the spectrum of a complex sound. The effects of parameters such as the number of components in the complex, their density, bandwidth, and whether the components are harmonic or equally spaced in logarithmic frequency will be described. Some new data on how signal duration affects the ability to detect spectral change will also be reviewed. It is believed that three distinct sets of cues mediate the detection of changes in the spectral shape depending on the total bandwidth of the complex. For wide bandwidths, the primary cue is a simultaneous comparison of level over different frequency regions. For spectra that are one or two critical bands in width, the primary cue is a change in pitch. For spectra less than one critical band, the primary cue is a change in the temporal fluctuation or roughness of the sound related to the power spectrum of the envelope.