Both spectral sparsity and lack of masker fluctuations contribute to release from masking.

Evidence

Consider first the results from the non-vocoded conditions (upper row of Fig. 3 ). Performance in the presence of Gaussian noise (GN; filled squares) is quite similar across the three groups but, as expected, performance is slightly poorer in the HI group. When the noise masker is replaced by 16 pure tones (PT; open circles), performance is markedly better—all three groups show a large improvement in performance, although there appears to be a systematic decrease in performance from young NH to age-matched NH to the HI group. Imposing noise envelope fluctuations to the pure-tone maskers (MT; filled circles) results in a small reduction in performance for all three groups. It appears that both the spectral sparsity of the tonal maskers (PT and MT), as well as the lack of fluctuations (PT), contributes to the release from masking relative to the GN condition. — Dijk, Pim van, Physiology, Psychoacoustics and…, 2188