One of the most successful elements of classic Doctor Who was the atmospheric sound effects which were provided by the BBC’s Radiophonic Workshop, which was a very experimental unit for electronic music and special sounds. Mostly the sound effects on the show were done by Brian Hodgeson during the sixties and early seventies, later they were done by Dick Mills.
One of the classic and most alien scores was the one composed for the first Dalek story, which while it might not be accurate, I will call The Daleks. It was composed by Tristan Cary and has a real unearthly sound to it and gives a real sense of alien to the scortched planet of Skaro.
However I think it goes without saying, that the hero of the Radiophonic Workshop, or rather heroine, was Delia Derbyshire. It was her who created the distinctive sound of the original Doctor Who theme. Ron Grainer may have composed the tune, but it was Delia who created the theme.
Delia’s pioneering work has finally been recognised as she was recently awarded a posthumous PhD.