Resolution of Rippled Spectra at Various Center Frequencies and Bandwidths of Sound Stimuli

Sound stimuli with rippled spectra are usable for testing the frequency resolving power of hearing. Estimates of the resolution depend on the center frequency and bandwidth of the test stimulus. In the present study, ripple density resolution was measured at various center frequencies and various bandwidths in two experimental paradigms: with the use of rippled or flat reference signals. With rippled reference signals, there was no statistically significant resolution dependence on either the center frequency or bandwidth. In all cases, the resolution was near 10 ripples/oct. With flat (nonrippled) reference signals, the ripple density resolution depended on both the center frequency and bandwidth: the higher the center frequency and the wider the frequency band, the higher the resolution was. The difference between resolution estimates obtained with different reference signals may be explained by different contributions of the spectral and temporal mechanisms of frequency analysis. The spectral (excitation pattern) mechanism is effective for discriminating between a rippled test and a rippled reference signal. The temporal processing mechanism is effective for discriminating between a rippled test and a flat reference signal.