History of Singing (1947)

Gino Fabretti is a famous Italian tenor. During a tour in Nice, he begins a relationship with the wife of a renowned doctor. The doctor traps and drugs him and replaces his vocal cords with those of Robert, a delivery boy in a grocery store. Robert wakes up with the voice of Gino and Gino with that of Robert (including accents and mannerisms!). The unfaithful wife despises the tenor without his voice and becomes more interested in the grocer.