The man known to many as “The Fifth Beatle” died this week.

Sir George Martin was 90 years old and best known as the producer who changed the world when he signed a contract with the unknown band The Beatles in 1962.

Music writer David Watts Barton has written, and talked, extensively about The Beatles during his career. He joins Insight for this week’s Sound Advice with a look back at how George Martin influenced one of the most popular bands of all time.