The author played clarinet in accompaniment with a singing male humpback whale off the coast of Maui. A sound spectrogram suggests that the whale may have altered his song in response to the clarinet. This observation is consistent with the fact that humpback whales rapidly change their song during breeding season from week to week. A male humpback whale may be able to quickly match new pitched, musical sounds it has never heard before—a result different from those of most humpback whale playback experiments. This experiment suggests that interspecies music-making might be a valuable tool in helping understand the complex communication strategies of humpback whales, as well as in extending our own music making beyond the human realm.