Well, I certainly recognize the actual voices of Christopher Lee, Peter Cushing and Telly Savalas. However, many of the other actors appear to be dubbed (probably because it had a foreign cast). The voice of the police detective sounds familiar to me but I can't place it.
shareIt seems as if a few segments were filmed without sound, with voices and effects laid in after. It was shot in Italy and I'd imagine some voices were substituted.
sharefrom the trivia section
Most of the film was shot without audio recording, the soundtracks and dialog were all added in post production. Stars Christopher Lee, Peter Cushing, and Telly Savalas provided their own voices for the film's English release