As shoppers stroll through Burlington’s Cascade Mall, they may hear some unusual noises coming from behind a black curtain strung across the front of an empty store. The shrieks and giggles of young girls are punctuated by what sounds like the booming commands of a personal trainer. The girls aren’t workout gurus or Marines. They’re dancers for Clan Heather, a Highland Dance company with studios in Mount Vernon, Everett and Bellingham. And the deep voice belongs to Tyler Amaya, the girls’ unlikely trainer.