Donald HobernSome Australian #Epipaschiinae have bulges in the forewing costa, along with messy scale tufts in the same area, but I'd expect scales to dampen any potential auditory effects. I always took it that structures like these are for spreading pheromones.
See also the forewings of these pug moths (#Geometridae #Eupitheciini):
https://inaturalist.ala.org.au/taxa/602535-Sigilliclystis-insigillata
