Speech Reductions Cause a De-Weighting of Secondary Acoustic Cues

The ability of the auditory system to change the perceptual weighting of acoustic cues when faced with degraded speech has long been evidenced. However, the exact changes that occur remain mostly unknown. Here, we proposed to use the Auditory Classification Image (ACI) methodology to reveal the acoustic cues used in natural speech comprehension and in reduced (i.e. noise-vocoded or re-synthesized) speech comprehension. The results show that in the latter case the auditory system updates its listening strategy by de-weighting secondary acoustic cues. Indeed, these are often weaker and thus more easily erased in adverse listening conditions. Furthermore our data suggests that this de-weighting does not directly depend on the actual reliability of the cues, but rather on the expected change in informativeness.