Answer: whistling

AnswerCrossword Clue
whistlingWHISTLE, to make a shrill sound
whistlingEmit a clear, high-pitched sound by forcing breath through a small hole between one's lips or teeth
whistlingProduce such a sound by moving rapidly through the air or a narrow opening
whistlingExpress surprise, admiration, or derision by making such a sound
whistling(esp. of a bird or machine) Produce a similar sound
whistlingSummon something or someone by making such a sound
whistlingWish for or expect (something) in vain
whistlingProduce (a tune) in such a way
whistlingBlow an instrument that makes such a sound, esp. as a signal