Understanding speech when multiple people are talking simultaneously relies on various perceptual and cognitive mechanisms, such as stream segregation, selective attention, and inhibition. Differences in voice characteristics, such as mean fundamental frequency (F0) and vocal-tract length (VTL), help discriminating between different voices and facilitate speech perception in the presence of competing speech. In older adults, speech perception difficulties become highly prevalent, particularly in noisy listening situations. Some studies on perceptual processing in older adults showed that older adults may be less sensitive to F0 differences, which could affect their ability to distinguish different speakers. Furthermore, age-related cognitive changes may lead to difficulties directing attention to relevant speech and inhibiting competing information. As a result, speech perception in the presence of interfering speech becomes particularly difficult for older adults. The first aim of this study was to investigate to what extent older adults, compared to younger adults, benefit from voice differences in a speech-on-speech (SoS) perception task. In another line of research, studies have suggested that musicians, compared to non-musicians, perform better in SoS tasks. However, this advantage has mostly been observed in younger adults, and it is not yet known if this advantage extends to older adults. It could be that musical training leads to improved processing of acoustic features such as F0, or improved stream segregation and selective attention abilities. This would protect older adults from declines in cognitive functioning and/or the ability to process acoustic features such as F0, such that age-related decline in SoS perception may be reduced in musically-active older adults. The second aim of this study was therefore to investigate whether a musician advantage in SoS perception exists for older adults. Together, this study explored the effects of aging and musical expertise on SoS perception by considering four experimental groups, namely younger (18-30 years) and older (60-80 years) adults with and without musical expertise, all with self-reported normal hearing. All participants performed an online Coordinate Response Measure test with a single target speaker and a single talker masker. Participants were asked to respond to keywords in the target speech, while target-to-masker ratios were varied, and differences in F0 and VTL voice cues between the target and competing voices were manipulated. We will report preliminary findings of this study and show to what extent aging effects and musical training may have an influence on speech perception in the presence of competing speech.