The role of excitation-pattern, temporal-fine-structure, and envelope cues in the discrimination of complex tones

The discrimination of bandpass-filtered harmonic (H) from inharmonic (I) tones (produced by shifting all components of the H tones upwards by a fixed amount in Hz) could be based on shifts in the pattern of ripples in the excitation pattern (EP) or on changes in the temporal fine structure evoked by the tones. The predictions of two computational EP models were compared with measured performance. One model used auditory filters with bandwidth values specified by Glasberg and Moore [(1990). Hear. Res. 47, 103-138] and one used filters that were twice as sharp. Stimulus variables were passband width, fundamental frequency, harmonic rank (N) of the lowest component within the passband, component phase (cosine or random), signal-to-noise ratio (SNR), and random perturbation in level of each component in the tones. While the EP models correctly predicted the lack of an effect of phase and some of the trends in the data as a function of fundamental frequency and N, neither model predicted the worsening in performance with increasing passband width or the lack of effect of SNR and level perturbation. It is concluded that discrimination of the H and I tones is not based solely on the use of EP cues.