The term 'Puppy Sound' can be broken down into three crossword solutions: YELP (4 letters), YIP (3 letters), and YAP (3 letters). All three of these words are onomatopoeic, meaning they imitate the sound they represent. YELP is a loud, sharp bark, usually used to express pain or fear. YIP is a high-pitched bark, often used to express excitement or joy. YAP is a short, sharp bark, usually used to express annoyance or displeasure. All three of these sounds are commonly made by puppies.