Stereotypic beliefs dominate reversal learning.

One of the common challenges people face in everyday life is understanding speech in noisy environments, which requires a finely tuned interaction between peripheral hearing and auditory-cognitive mechanisms. About 42% of individuals report having difficulty perceiving speech-in-noise (SPIN) despite having normal hearing thresholds (). SPIN difficulties can be a major health burden, as they may lead to social withdrawal and loneliness, and can be linked—directly or indirectly—to cognitive decline, ultimately affecting quality of life (; ; ; ). Given these broad consequences, it is practically important to understand why some individuals cope well with speech in the presence of competing talkers while others struggle. Untangling the factors behind these differences, and understanding how they affect SPIN and to what extent, would be the first step towards developing strategies to manage SPIN difficulties. One group that seems to have an advantage in understanding speech in noisy environments is people who engage in music, such as those who play an instrument or actively participate in musical activities like singing. There is growing evidence suggesting that musicians, or individuals who have undergone musical training for some period of time, outperform non-musicians in SPIN perception (; ; ; , ; ). However, other studies have reported no such advantage (; , ; ). One possible reason for these mixed findings is that different SPIN paradigms place different perceptual and cognitive demands on the listener. In particular, listening conditions in which speech is masked by competing speech may increase informational masking and place greater demands on higher-level processes such as selective attention and auditory stream segregation, which may be more sensitive to musical experience (; ). It is also possible that musical training affects speech-on-speech processing in ways that do not always translate into better behavioural SPIN performance. For example, musicians may show earlier disambiguation of target speech from background, possibly due to training-related advantages in processes relevant to stream segregation, suggesting a more efficient or different listening strategy rather than necessarily better performance (). A meta-analysis by reported a consistent musician advantage in SPIN perception, irrespective of age, speech material, or IQ. Another line of evidence supporting this advantage comes from longitudinal studies showing that engaging in musical activities over time leads to improved SPIN perception (; ; ). However, findings are not entirely consistent, and a recent review reported that the evidence for transfer from music training to non-musical abilities is weak, and that pre-existing individual differences may account for many such associations (). Although many longitudinal studies also lack an active control group, a recent study that included an active, non-musical control group reported SPIN benefits from music training in cochlear implant users (). To explain the roots of this effect, the OPERA hypothesis (overlap, precision, emotion, repetition, and attention) proposes that shared auditory-cognitive mechanisms involved in processing music and speech are strengthened through musical training, depending on the degree of engagement (e.g., emotional reward, repetition, and attentional focus) (, ). Specifically, speech and music perception are thought to rely on overlapping neural pathways and structures, from subcortical to cortical levels, where acoustic input is progressively processed and represented. Music processing also places particularly high demands on precision, as it requires fine-grained analysis of pitch, timing, and periodicity, all of which are also relevant to speech processing. In addition, musical activities are often emotionally rewarding, highly repetitive, and attentionally engaging, all of which may help drive plastic changes in the brain. Repetition gives listeners more chances to practise, attention helps them focus on the relevant sounds, and emotional reward may help keep them engaged and motivated to learn. The extent to which these shared mechanisms contribute to both speech and music processing is still being investigated, though several possible links have been proposed. From first principles, the ability to group and maintain auditory elements over time is essential for forming auditory streams and achieving sound segregation. This ability enables both SPIN understanding and music processing by allowing us to sustain attention and retain relevant information in working memory. A large body of research on the role of working memory in SPIN perception suggests that, beyond peripheral hearing, the ability to hold relevant information in mind supports SPIN performance, such that the better one’s working memory, the better the understanding of SPIN (; ; ; ; ; ; ), but see . Similarly, engaging in musical activities has been associated with enhanced working and short-