Temporal integration of loudness under partial masking

Abstract

This paper tests the hypothesis that the loudness ratio between equal-SPL tones with different durations is the same at all SPLs. Detection thresholds and levels required to produce equal loudness for 5- and 200-ms tones presented in quiet or in broadband noise were measured using adaptive, two-interval, two-alternative forced-choice procedures. Tone levels ranged from 5 dB SL to 90 dB SPL for the long tones and about 100 dB SPL for the short tones. Results from six listeners with normal hearing show that the amount of temporal integration, defined as the level difference between equally loud 5- and 200-ms tones, varies nonmonotonically with level and is greatest at moderate levels. The average amount of temporal integration in quiet is about 15 dB near threshold, increases to a peak of 27 dB when the 5-ms tone is about 58 dB SPL, and decreases to about 15 dB near 100 dB SPL. For masker levels of 40, 60, and 80 dB SPL, the amount of temporal integration near masked threshold remains near 15 dB. The maximum amount of temporal integration decreases as masker level increases and occurs at progressively higher levels. At high levels, the amount of temporal integration is nearly the same as in the quiet for all masker levels. Loudness functions derived by applying the equal-loudness-ratio hypothesis to the data yield excellent predictions of loudness matches between tones in the quiet and partially masked tones with the 40- and 60-dB maskers. For the 80-dB masker, clear deviations are present. These results support the equal-loudness-ratio hypothesis, but suggest that intense masking may alter the loudness ratio between 200- and 5-ms tones.

Temporal integration of loudness in listeners with hearing losses of primarily cochlear origin

“…The average amount of temporal integration at 5 dB SL was about 13 dB in the present study, similar to the values of about 12 dB obtained by Florentine et al ͑1996͒ and 15 dB obtained by Florentine et al ͑1998͒. Likewise, the amount of temporal integration obtained at 90 dB SPL in the present study was 13 dB, which is close to the 11 dB reported by Florentine et al ͑1996͒ and 14 dB reported by Florentine et al ͑1998͒.…”

“…Likewise, the amount of temporal integration obtained at 90 dB SPL in the present study was 13 dB, which is close to the 11 dB reported by Florentine et al ͑1996͒ and 14 dB reported by Florentine et al ͑1998͒. The maximal amount of temporal integration of the average data was 26 dB in the present study, which is close to the maximum of 27 dB obtained by Florentine et al ͑1998͒ but somewhat larger than the 18 dB obtained by Florentine et al ͑1996͒. Given that the individual listeners in the three studies show maxima varying from about 12 to about 36 dB, it is not surprising that the maximal amounts of temporal integration vary somewhat across studies.…”

“…The average amount of temporal integration at 5 dB SL was about 13 dB in the present study, similar to the values of about 12 dB obtained by Florentine et al ͑1996͒ and 15 dB obtained by Florentine et al ͑1998͒. Likewise, the amount of temporal integration obtained at 90 dB SPL in the present study was 13 dB, which is close to the 11 dB reported by Florentine et al ͑1996͒ and 14 dB reported by Florentine et al ͑1998͒. The maximal amount of temporal integration of the average data was 26 dB in the present study, which is close to the maximum of 27 dB obtained by Florentine et al ͑1998͒ but somewhat larger than the 18 dB obtained by Florentine et al ͑1996͒.…”

“…The effect of level is important because the amount of temporal integration varies markedly with level in normal listeners ͑e.g., Stephens, 1973;Poulsen, 1981;Florentine et al, 1996Florentine et al, , 1998 and the outcome of comparisons between normal and impaired hearing appears to depend on the SPL ͑Pedersen and Poulsen, 1973͒. The outcome may also depend on whether normal and impaired listeners are compared at equal SL or equal SPL, as indicated by the contrast between temporal integration for detection ͑an equal-SL comparison͒ and for loudness ͑compared at equal SPLs͒.…”

“…Because most natural sounds are not steady state, but have amplitude peaks that typically are much shorter than the 50-150-ms integration time generally assumed for loudness ͑for review, see Scharf, 1978͒, knowledge of the loudness functions for brief sounds may be important for hearing-aid fitting and for general understanding of impaired listeners' auditory perception. Moreover, our recent studies ͑Florentine et al, 1996;Florentine et al, 1998͒ indicate that temporal integration of loudness may provide rather direct information about the form of the loudness functions for both brief and long sounds.…”