Pain is an unpleasant experience the neurobiology of which is influenced by psychosocial factors including negative affect. Music is a ubiquitous experience that can improve affect, potentially decreasing anxiety and catastrophizing, both of which are associated with greater pain severity. We hypothesized that a machine-learning generative music intervention in the form of a smartphone web app (Unwind) could be used to modulate the experience of pain. In this pilot study, we recruited 15 individuals with acute pain who were admitted to an observation unit in the emergency department, and were being treated with opioids. Participants used the music intervention (Unwind) during this brief hospitalization, after which we assessed their response to its use through a semi-structured qualitative interview. Overall, participants responded positively to Unwind. While some reported some technical challenges, participants were willing to continue using it at home. In particular, participants reported using Unwind to address their anxiety, and many used it to facilitate sleep in the presence of pain. This study demonstrates that individuals with acute pain will accept and use a smartphone-based music protocol.