Left-hand panels: 50 ms epochs of the time-waveforms of 4-kHz-centered raised-sine stimuli modulated at 128 Hz and having exponents of 1, 2, 4, and 8 (rows 1–4, respectively) and of a 4-kHz-centered transposed stimulus modulated at the same rate (bottom row). Right-hand panels: Each row depicts the corresponding long-term power spectrum of the time-waveform shown immediately to its left.
Mean normalized threshold ITDs, calculated across the four listeners as a function of the exponent of the raised-sine stimulus. Normalized threshold ITDs obtained with the transposed stimuli are plotted at the far right. The normalization was accomplished by dividing an individual listener’s threshold ITDs by that listener’s threshold ITD obtained with a SAM tone (raised-sine exponent equal to 1.0) having a frequency of modulation of 128 Hz. The individual threshold ITDs for that reference stimulus were 128, 271, 113, and . The parameter of the plot is the frequency of modulation. Error bars represent standard error of the mean normalized thresholds.
Mean normalized threshold ITDs. Each of the four sections of the figure contains data obtained with a single depth of modulation and raised-sine exponents having values of 1.0, 1.5, or 8.0. Error bars represent standard error of the mean. The time-waveforms corresponding to four of the stimuli are depicted atop their corresponding bars.
A re-plotting of the normalized threshold ITDs from Fig. 2 (squares). Each panel contains the data obtained with one of the four frequencies of modulation. The solid lines represent predictions obtained from an interaural correlation-based model incorporating a final stage of second-order (12 dB/octave) low-pass filtering at 150 Hz. The dashed lines represent predictions obtained from the same model but with a final stage of first-order (6 dB/octave) low-pass filtering at 150 Hz.
Normalized threshold ITDs re-plotted from Fig. 3 (bars) along with two sets of predictions (symbols). The predictions were generated via the interaural correlation-based model using a final stage of first-order low-pass filtering at 150 Hz. Predictions represented by the closed squares were calculated using same criterion change in interaural correlation that provided the best-fitting (dashed-line) predictions shown in Fig. 4. Predictions represented by the open triangles were calculated using the criterion correlation that yielded the model’s best fit to those thresholds.
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