Difficulties with speech-in-noise perception related to fundamental grouping processes in auditory cortex

In our everyday lives, we are often required to follow a conversation when background noise is present (\"speech-in-noise\" perception). Speech-in-noise perception varies widely--and people who are worse at speech-in-noise perception are also worse at fundamental auditory grouping, as assessed by figure-ground tasks. Here, we examined the cortical processes that link difficulties with speech-in-noise perception to difficulties with figure-ground perception using functional magnetic resonance imaging (fMRI). We found strong evidence that the earliest stages of the auditory cortical hierarchy (left core and belt areas) are similarly disinhibited when speech-in-noise and figure-ground tasks are more difficult (i.e., at target-to-masker ratios corresponding to 60% than 90% thresholds)--consistent with increased cortical gain at lower levels of the auditory hierarchy. Overall, our results reveal a common neural substrate for these basic (figure-ground) and naturally relevant (speech-in-noise) tasks--which provides a common computational basis for the link between speech-in-noise perception and fundamental auditory grouping.