The term 'Happy Sound' can be represented by four different crossword solutions: PURR (4 letters), LAUGHTER (8 letters), COO (3 letters), and CHIRP (5 letters). Purring is a low, vibrating sound made by cats, often when they are content. LAUGHTER is a sound made when someone is amused or happy. Cooing is a soft, gentle sound made by doves and other birds. Chirping is a high-pitched sound made by birds, often in the morning. All of these sounds are associated with happiness and joy.