James (Jim) Martyn started his career in radio before merging that experience with motorsports, when he volunteered to assist the Mosport Park track announcer with calling a 24-hour race in 1987. That led to his official involvement with the legendary track, now Canadian Tire Motorsport Park, the following weekend. He held the role of PA announcer until his death in October 2019.

Martyn was the PA announcer for the American Le Mans Series from 1997 to 2010 and was part of the broadcast of the inaugural Petit Le Mans, the second major sporting event to be available via internet for worldwide reach. He was also the voice used as background commentary in the Sports Car GT video game in 1999 and was part of Motorsport Radio on Sportsnet 590 and Car Guys on Global TV.