Probably the same thing -- its a function of gas density and the mechanics of reed vibration, in the same way that a chanter has a reed and a volume of gas interacting to make the sound. But it's a lot harder to limit the gas supply to helium with an accordion because it's open to atmosphere in a lot of places, I expect. You'd have to build one customized to only draw through a couple of pipes hooked up to a helium tank!

Maybe Spaw would do it as a contribution to instrumental science?

A