couac / quack [kwæk]
couac – n. – the strident tone sometimes produced by a reed instrument when the reed is out of order or when the instrument is blown incorrectly
quack – n. & v. tr. – n. – 1. the sound made by ducks; 2. an unqualified practitioner of medicine; 3. of or characteristic of unskilled medical practice; 4. a charlatan; 5. British, Australian, & New Zealand slang any doctor or medical officer; v. intr. – 1. utter the sound of a duck; 2. informal talk loudly and foolishly