Spectral loudness summation for sequences of short noise bursts

Recent loudness data of single noise bursts indicate that spectral loudness summation depends on signal duration. To gain insight into the mechanisms underlying this duration effect, loudness was measured as a function of signal bandwidth centered around 2 kHz for sequences of 10-ms noise bursts at various repetition rates and, for comparison, for single noise bursts of either 10- or 1000-ms duration. The test-signal bandwidth was varied from 200 to 6400 Hz. For the repeated noise bursts, the reference signal had a bandwidth of 400 Hz. For the single noise bursts, data were obtained for two reference bandwidths: 400 and 3200 Hz. In agreement with previous results, the magnitude of spectral loudness summation was larger for the 10-ms than for the 1000-ms noise bursts. The reference bandwidth had no significant effect on the results for the single noise bursts. Up to repetition rates of 50 Hz, the magnitude of spectral loudness summation for the sequences of noise bursts was the same as for the single short noise burst. The data indicate that the mechanism underlying the duration effect in spectral loudness is considerably faster than the time constant of about 100 ms commonly associated with the temporal integration of loudness.