Lou Ottens, the Dutch inventor of the cassette tape, has died aged 94. (Photo: Wikipedia)

The cassette tape was Ottens' answer to the large reel-to-reel tapes that provided high-quality sound but were seen as too clunky and expensive.

An estimated 100 billion cassette tapes have been sold around the world since they were introduced in the 1960s.

Ottens' invention transformed the way people listened to music, and there has even been a resurgence of the cassette in recent years.