Yes, Jasper yawns without a sound, but Piddle and Wiggles sound alot like Tommy, if they are playing or in a good mood, the yawn is a higher pitch, and a bit longer lol and if they are tired or sick its a whole different yawn.

Piddles yawns sometimes sound like cries, little yelps lol

And wiggles yawns sometimes sound like playfull growls, or something like that.