Reverberation and natural pitch modulation combine to impair vowel segregation more than either alone

Evidence

The effects of noise and reverberation on double-vowel segregation are not equivalent. The results can be summarized as: (1), There is a strong interaction between F0 modulation (simulating intonated speech) and reverberation to reduce template contrast. (2), There is no interaction between F0 modulation and signal-to-noise ratio. (3), Noise-induced deficits in neural periodicity-based double-vowel segregation are strongly BF-dependent, due to more total (masking) noise power passed by higher-BF filters. (4), Reverberation impairs neural segregation of intonated double vowels independent of BF, but has only marginally detrimental effects on segregation of double vowels with steady F0s. — Dijk, Pim van, Physiology, Psychoacoustics and…, 5025

We recorded responses to single and double vowels, in anechoic and reverberant conditions, from 129 units with BFs between 0.1 and 6 kHz (36 primary-like [PL/PN], 47 chopper [CT/CS], 24 onset [OC/OL], 19 low-frequency [LF], 3 unusual [UN]). From 52 of these, we also recorded responses to vowels in noise. The effects of noise and reverberation on double-vowel segregation are not equivalent. The results can be summarized as: (1), There is a strong interaction between F0 modulation (simulating intonated speech) and reverberation to reduce template contrast. (2), There is no interaction between F0 modulation and signal-to-noise ratio. (3), Noise-induced deficits in neural periodicity-based double-vowel segregation are strongly BF-dependent, due to more total (masking) noise power passed by higher-BF filters. (4), Reverberation impairs neural segregation of intonated double vowels independent of BF, but has only marginally detrimental effects on segregation of double vowels with steady F0s. — Dijk, Pim van, Physiology, Psychoacoustics and…, 5048

The double-vowel sounds are well segregated on the basis of the periodicity-tagged discharge rate statistic, except when F0 is modulated and the sounds are heard in “moderate” or “strong” reverberation (Fig. 6a ). — Dijk, Pim van, Physiology, Psychoacoustics and…, 5069

Categorization

• QUESTION: Why does F0 modulation interact with reverberation but not with noise? The dissociation suggests different degradation pathways worth investigating.
• XREF: Connects to classic Auditory Scene Analysis work (Bregman) on concurrent vowel segregation and the ‘double vowel problem’ in psychoacoustics.
• corroborated: 3 independent passages support this claim — Dijk, Pim van, Physiology, Psychoacoustics and…, 5025; Dijk, Pim van, Physiology, Psychoacoustics and…, 5048; Dijk, Pim van, Physiology, Psychoacoustics and…, 5069