Noise and reverberation reduce modulation depth but preserve signal shape

Evidence

The physical effects of noise and reverberation have some similarities: small changes to the magnitude and phase of each component of a complex sound. The impulse response of a room is a linear filter. Therefore, for a steady-state source no new frequency components are added to a reverberant acoustic signal. Contrast this with additive noise. Each indirect sound component in a reverberant space adds to the direct sound at the receiver with essentially random phase, reducing the depth of temporal-envelope modulation at the output of cochlear band-pass filters (Sabine 1922 ; Sayles and Winter 2008 ; Sayles et al. 2015 ; Slama and Delgutte 2015 ). — Dijk, Pim van, Physiology, Psychoacoustics and…, 5070

Categorization

• DEFINE: Clarifies the acoustic distinction between reverberation (linear filtering, no new frequencies) and additive noise.
• corroborated: 2 independent passages support this claim — Dijk, Pim van, Physiology, Psychoacoustics and…, 5070
• XREF: connects to: Filtered-target and filtered-noise experiments reveal SNR floor and ceiling limits