Here’s a radio interview with Mitchell Gaynor who, amongst other things, wrote the book The Healing Power of Sound: Recovery from Life-Threatening Illness Using Sound, Voice, and Music
Here’s an article on sound baths in the New York Times from August 2015
Here’s an article/video on the origins of Zildjian’s cymbal making
Here’s an article/video on ancient Rock Gongs
Here’s a BBC news clip abut gong baths.