An essential part of music teacher education is supervised teaching practice. In instrumental teaching, this practice usually comprises a student teaching one or more pupils on their instrument, a schoolteacher, and/or a practice supervisor that gives feedback to the student. The rationale for this format is that supervised practice is part of a socialization process where future teachers must acquire knowledge, norms, and values as a basis for their work as teachers. In this article, pupil participation in feedback in the supervision of instrumental teacher students is explored, based on theories of dialogic pedagogy and philosophy. The starting point for the discussion is a pilot study where we explored the learning potential of including the pupil’s voice in the supervised practice in a music school. In the academic year 2021/2022, the study was carried out where an instrumental teacher student received feedback on his teaching from both the supervisor and the pupil being taught. The supervised practice comprised a session where all three participants watched a recording of the teaching situation, and the pupil participated in the discussion about, and the analysis of, the content and execution of the lesson. The results are discussed in light of theories about dialogicity in art educational practices understood through, among others, Mikhail Bakhtin, Hartmut Rosa and Anne Bogart. The study shows that there are new possibilities for dialogic processes in the development of professional competence as an instrumental teacher by involving the pupils in the supervised teaching practice.