Schwaaah schwaah!

NOT "Oom pah pa." That's talking like TUBAS, not like accordions (and not even like sousaphones, which have come to have a much broader vocabulary than their cousins the tubas).

In fact, "schwaaa/schwaaa" (I'm not really sure how to spell it) is a colloquial Cajun word FOR accordion/squeezebox.

(By the way, there another thread, an older one, for those responding to the request "Can we talk about accordions please?" This is a distinctly different topic, "Can we please talk LIKE accordions please?")