Results for the broadband noise, random-phase tones, and chirp tones, both chirp↓ and chirp↑. The plot shows the mean response to each of the five polar angles of the source locations for one listener, listener V. Perfect responses would fall along the dashed 45° line. Error bars show standard errors. The number of front-back reversals for sources in front and in back are given together with the total . The slope is otherwise known as the “polar-angle gain.” Parameters and are the rms error and standard deviation (see text). The left and right column are for 50 and 70 dBA SPLs, respectively.
Three statistics, averaged over five listeners for four waveforms in experiment 1: broadband noise, random-phase tones, chirp↓, and chirp↑. High (◻) and low (●) levels are 70 and 50 dB SPL. Error bars are two standard deviations in overall length.
Same as Fig. 1 except for high-pass noise and tones in experiment 2.
Same as Fig. 2 except for high-pass noise and tones in experiments 2 and 3. High (◻) and low (●) levels were 70 and 50 dB SPL.
Results for high-pass stimuli as in Fig. 3, but for different phase relationships, cosine-phases, and sine-phases in experiment 3.
Linear response of a gammatone filter bank to periodic tones used in experiments 2 and 3 represented at six different places on the model basilar membrane. The small effect of cochlear delays can be seen for cosine-phase where excitation at the 15-kHz place occurs about 1 ms before excitation at the 5-kHz place. For the chirp↑ tones there is negligible temporal overlap between excitation at 15- or 13-kHz places and excitation at the 9-kHz and lower places. The filter bank has equivalent rectangular band widths given by Glasberg and Moore (1990).
Same as Fig. 4 except that the auditory filter bandwidths have been divided by a factor of 8. Also, the amplitudes of excitation patterns have been multiplied by a factor of 3 for better comparison with Fig. 4. For the chirp↑ tones there is considerable temporal overlap of excitation at all places, and the response to the pulse train is extended in time.
Overlap for 15 pairs of bands as a function of auditory filter bandwidth. A bandwidth of 1 Cam corresponds to Cambridge equivalent rectangular bands, called “normal” in the text. Other bandwidths are smaller by factors of 2, 4, 6, and 8. Different symbols indicate different band pairs, described by center frequencies in kilohertz: Filled circles 7–5 and 9–7. Filled squares 11–9 and 13–11. Filled triangles 15–13. Open circles 9–5, 11–7, and 13,9. Open squares 11–5. Open triangles 15–11. Open diamonds 13–7 and 13–5. Plus signs, 15–9, 15–7, and 15–5. Overlaps computed for bandwidths of Cam and Cam/8 correspond to Figs. 6 and 7, respectively.
Total number of front-back reversals expressed in the form . 100% errors for both levels would be . Values in parentheses for listeners G and R are for 40 dB.
Polar-angle gain (slope) expressed in the form . Values in parentheses for listeners G and R are for 40 dB.
rms error , rounded to integer degrees and expressed in the form . Values in parentheses for listeners G and R are for 40 dB.
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