Which principle involves matching music to a client's mood initially?

The Iso Principle focuses on aligning the music used in therapy with the client's current emotional state or mood. This approach is rooted in the idea that to effectively engage clients and facilitate therapeutic progress, it is essential to start where they are emotionally. By matching the music to a client's mood, the therapist can create a sense of connection and understanding, which can help build rapport and trust.

For example, if a client is feeling sad or withdrawn, playing music that reflects these emotions can provide comfort and validation. This alignment allows for gradual shifts to more uplifting or dynamic music as the client's mood changes, promoting emotional processing and improvement.

The other principles listed, such as the Therapeutic Principle, Insight Principle, and Emotive Principle, while relevant in the broader context of music therapy, do not specifically focus on the initial matching of music to a client's mood, which is the core concept of the Iso Principle.