Temporal loudness integration and spectral loudness summation in normal-hearing and hearing-impaired listeners

The aim of this study was to test for differences between normal-hearing an d hearing-impaired listeners regarding two fundamental aspects of intensity perception: loudness integration and loudness summation. Loudness function s for three different stimuli were measured using categorical loudness scal ing in 8 normal-hearing and 12 hearing-impaired subjects. The results indic ated that temporal loudness integration. defined as the difference in SPL b etween 16.25-ms and 300-ms noise bursts of equal loudness, was larger in th e hearing-impaired than in the normal-hearing listeners. Loudness summation . defined as the difference in SPL between a 300-ms. 1.600-Hz tone pip and a white noise burst of the same duration and loudness. did not differ betwe en the two groups. Implications of these results for hearing aid fitting st rategies based on loudness normalization are discussed.