Effect of signal duration on categorical loudness scaling in normal and inhearing-impaired listeners

The present study sought to determine whether the duration of white-noise b ursts affects their loudness category rating in the same way for hearing-im paired as for normally-hearing subjects. Twelve normally-hearing and 12 hea ring-impaired subjects took part. Categorical loudness growth functions wer e obtained for 16.25 ms, 32.5 ms, 75 ms, 150 ms and 300 ms white noise burs ts. Temporal integration of loudness was defined as the intensity differenc e needed for stimuli of different durations to result in identical category ratings. In normally-hearing subjects, temporal integration of loudness oc curred mainly with the short-duration (16.25 ms and 32.5 ms) stimuli, where as it was found with almost every stimulus duration in hearing-impaired sub jects. In other words, temporal integration of loudness between 16.25 ms an d 300 ms stimulus duration was greater in hearing-impaired listeners and th ere was a difference between normal and hearing-impaired subjects regarding change in loudness perception with stimulus duration. Consequently, the us e of fixed-duration stimuli hinders loudness normalization.