Whistle

Some whistles are happy-oriented, like when someone wants to offer over-the-top praise for a hero at a public event by placing fingers in mouth like the Texas hook-em-horns symbol and belt out a sound higher pitched than a finishing note from Celine Dion.  Dogs don't whistle and that might not be a bad thing.  A loud bark is the near-equal anyway.  Whistling is mainly negative, think referees, and dogs just stay positive mostly.