Home / Forums / Melodica construction, repair and maintenance / Yamaha P37D, muffled sounds due to clogged spit / Reply To: Yamaha P37D, muffled sounds due to clogged spit Reply To: Yamaha P37D, muffled sounds due to clogged spit March 21, 2018 at 4:43 pm #9775 Jerry BallardParticipant #3 (slapping instrument to dislodge moisture) is a common harmonica practice.