Journal of The Acoustical Society of America - J ACOUST SOC AMER, 2001
Van Schijndel et al. ͓J. Acoust. Soc. Am. 105, 3425-3435 ͑1999͔͒ have proposed that the internal ... more Van Schijndel et al. ͓J. Acoust. Soc. Am. 105, 3425-3435 ͑1999͔͒ have proposed that the internal excitation evoked by an auditory stimulus is segmented into ''windows'' according to the stimulus spectrum and stimulus length. This ''multiple looks'' model accounts for the mid-duration hump they observed in plots of intensity-difference limens ͑DLs͒ versus pip duration for Gaussian-shaped 1-and 4-kHz tones, an effect replicated by Baer et al. ͓J. Acoust. Soc. Am. 106, 1907-1916 ͑1999͔͒. However, van Schijndel et al. and Baer et al. used few levels. A greater number of levels were used by Nizami ͑1999͒ for Gaussian-shaped 2-kHz tone-pips whose equivalent rectangular duration ͑D͒ was 1.25 ms. The DLs show the mid-level hump known for clicks ͓Raab and Taub, J. Acoust. Soc. Am. 46, 965-968 ͑1969͔͒. At some duration this pattern must become the ''near-miss to Weber's law.'' To determine this duration, as well as the level-dependence of the mid-duration hump, DLs were established for Gaussian-shaped 2-kHz tone-pips of Dϭ1.25, 2.51, and 10.03 ms at levels of 30-90 dB SPL. The across-subject average DLs for the tone-pips rise up at mid-levels for Dϭ1.25 and Dϭ2.51 ms. The DLs for Dϭ2.51 ms are larger, creating the mid-duration hump. At all durations, the new DLs are smaller at high levels than at low levels, consistent with the near-miss to Weber's law. DLs were also obtained here for Gaussian-shaped broadband-noise pips of Dϭ0.63, 1.25, 2.51, 5.02, and 10.03 ms. The DLs for the noise-pip show a mid-level hump for all pip durations. The noise-pip DLs decrease as the pip lengthens, such that the plot of DL versus log duration shows a linear decline, with no mid-duration hump. Analysis of variance reveals that the mid-level hump coexists with the classical patterns of level-dependence, perhaps reflecting the existence of two level-encoding mechanisms, one that depends on firing-rates counted over single neurons and which is responsible for the classical patterns, and one that depends on the initial coordinated burst of neuronal spikes caused by rapid ramping, and which presumably causes the mid-level hump.
Journal of The Acoustical Society of America - J ACOUST SOC AMER, 2001
Van Schijndel et al. ͓J. Acoust. Soc. Am. 105, 3425-3435 ͑1999͔͒ have proposed that the internal ... more Van Schijndel et al. ͓J. Acoust. Soc. Am. 105, 3425-3435 ͑1999͔͒ have proposed that the internal excitation evoked by an auditory stimulus is segmented into ''windows'' according to the stimulus spectrum and stimulus length. This ''multiple looks'' model accounts for the mid-duration hump they observed in plots of intensity-difference limens ͑DLs͒ versus pip duration for Gaussian-shaped 1-and 4-kHz tones, an effect replicated by Baer et al. ͓J. Acoust. Soc. Am. 106, 1907-1916 ͑1999͔͒. However, van Schijndel et al. and Baer et al. used few levels. A greater number of levels were used by Nizami ͑1999͒ for Gaussian-shaped 2-kHz tone-pips whose equivalent rectangular duration ͑D͒ was 1.25 ms. The DLs show the mid-level hump known for clicks ͓Raab and Taub, J. Acoust. Soc. Am. 46, 965-968 ͑1969͔͒. At some duration this pattern must become the ''near-miss to Weber's law.'' To determine this duration, as well as the level-dependence of the mid-duration hump, DLs were established for Gaussian-shaped 2-kHz tone-pips of Dϭ1.25, 2.51, and 10.03 ms at levels of 30-90 dB SPL. The across-subject average DLs for the tone-pips rise up at mid-levels for Dϭ1.25 and Dϭ2.51 ms. The DLs for Dϭ2.51 ms are larger, creating the mid-duration hump. At all durations, the new DLs are smaller at high levels than at low levels, consistent with the near-miss to Weber's law. DLs were also obtained here for Gaussian-shaped broadband-noise pips of Dϭ0.63, 1.25, 2.51, 5.02, and 10.03 ms. The DLs for the noise-pip show a mid-level hump for all pip durations. The noise-pip DLs decrease as the pip lengthens, such that the plot of DL versus log duration shows a linear decline, with no mid-duration hump. Analysis of variance reveals that the mid-level hump coexists with the classical patterns of level-dependence, perhaps reflecting the existence of two level-encoding mechanisms, one that depends on firing-rates counted over single neurons and which is responsible for the classical patterns, and one that depends on the initial coordinated burst of neuronal spikes caused by rapid ramping, and which presumably causes the mid-level hump.
Uploads
Papers by Jason Reimer