Masking release based on comodulation of target and cue band

Comodulation of masker components can have opposite effects on detection performance: In a simple tone-innoise task, by adding comodulated masker components outside of the critical band, the performance of tone detection is improved. This effect has been termed Comodulation Masking Release (CMR, [2]). Otherwise, if comodulated flanking bands are presented in a modulation detection task, the performance of modulation detection is degraded, an effect called Modulation Detection Interference (MDI, [7]). CMR is often mentioned as one factor contributing to speech intelligibility in background noises. It has been suggested that, analogue to a single tone, speech signals can be detected better if the background signal is comodulated (e.g. [4]). In this specific context, it is usually not mentioned that also the speech signal itself is comodulated over a great frequency range due to envelope comodulation and due to common pitch. Possibly this comodulation also improves speech intelligibility. More specifically, it is the question whether this effect could hold for formant discrimination in the presence of a lowfrequency noise masker. Assuming a CMR effect, highfrequency comodulated side bands would help to identify the modulation of formant-like sounds and therefore performance may be improved. However, based on reports on MDI, one might expect that the presence of the strong pitch-based modulation at high frequencies would diminish the ability to detect the modulations caused by the low-frequency formant bands. Therefore, in this experiment, the influence of high-frequency band comodulation on discriminability of narrow-band tone complexes which simulate speech formants is investigated.