I only knew this 75 minute obscurity existed because it's a featurette on The Hanging Woman DVD released by Troma. After watching the excellent extras including an interview with Hanging Woman director Jose Luis Merino and Ben Tatar, director of dubbing for Sweet Sound, I decided to watch the film,produced by Sid Pink during his Spanish period. It turned out to be one of the best ghost movies I've ever seen, incredibly creepy, disturbing and chilling. I thought it was better than any ghost story I've ever seen including The Univited and The Haunting; very close in a way to the Euro equivalent of the original Carnival of Souls in style and mood. The black & white location photography is perfect and the music score during key moments is equally chilling. Without violence, monsters, gore or editing/camera tricks, Sweet Sound creates an unsettling, spooky ambiance that clings long after the troubling ending. I don't recall reading about this movie in Sid Pink's autobiography. Thanks to Troma for finding a good print and including it.