By Battle The man who invented the audio cassette tape has died at the age of 94. Lou Ottens was a Dutch engineer who helped develop the portable tape recorder in 1960. Annoyed with the clunky design of reel-to-reel tapes, he introduced the cassette tape three years later. More than 100 million cassette tapes have been sold over the years - the format has even made a comeback in recent years with retro music fans. What was your first music format - vinyl, cassettes, or CDs? Do you still have a working tape player?