It is premature to conclude that music is an adaptation. Given the danger of overextending the adaptationist mode of explanation, the default position should be the byproduct hypothesis, and it should take very strong evidence to drag us into the adaptationist camp. As yet, the evidence isn't strong enough - and the proposed adaptationist explanations have a number of unresolved difficulties.
* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.