This is a very interesting historical design from the UK.  In addition to the technical approach, learning about it leads to the interesting life of Edmund Wigan, the BBC R&D division, the BBC Radiophonic Workshop and Delia Derbyshire.  

See the 10 minute video, Pioneers Of Sound here  

See the tribute book about Edmund Wigan, Memories of Dad here 

See the 24 minute video, Delia Derbyshire - The Delian Mode here