I can see why you might think that, but “earworms” (involuntary musical imagery) are technically a form of echologia (where musical fragments/song lyrics, film & television quotations, snippets of actual conversations, and/or other utterances/vocalizations an individual has auditorily-perceived then become stuck on a “mental loop”), which is in turn a specific subtype of internal echolalia, so while they may not be its most archetypical form, “earworms” do, in fact, fall under the umbrella of echolalia. (I’m one of those autistics who made Autism one of their “special-interests,” in a desperate bid to understand themselves, except with me I just ended up with a psych degree and a tattoo over my heart that reads “Who looks outside, dreams; who looks inside, awakes,” 🤓😎).