Scott Muni, who died Tuesday at age 74, was a radio disc jockey who introduced generations of New Yorkers to the Beatles and Led Zeppelin, and whose deep voice defined drive-time rock and roll for more than three decades.

He once said that his was a voice “with treads in it.”

After working at WNEW-FM for 31 years, he was unceremoniously dumped when the station shifted to a more highly structured pop music format. Within a year he found a job at the “classic rock” formatted Q104.3, where he continued to spin many of the discs he himself had introduced to New York airwaves. He stopped working in January, when he suffered a stroke.

Muni was one of the early advocates of “freeform” radio, in which the DJ sets his own playlist, often on the spur of the moment. From his longtime perch as program director at WNEW, he was able to popularize freeform through a stable of DJs who set the tone for rock and roll radio into the 1990s: Pete Fornatale, Alison Steele, Rosko, Jonathan Schwartz, Meg Griffin, Dennis Elsas, and a host of others. They called him “Scottso,” or “The Professor” for his encyclopedic knowledge of musicological lore.

Over the years, Muni interviewed much of rock’s royalty from his perch at WNEW, including Paul McCartney, Mick Jagger, Pete Townsend, and Bruce Springsteen. In one of his more memorable encounters, the Associated Press reported, Muni was speaking with Led Zeppelin guitarist Jimmy Page when the musician collapsed to the floor in midsentence, wiped out by days of partying. Muni simply put on a record, woke up Mr. Page, and conducted the rest of the interview with the guitarist lying on the studio floor.

Muni was born in Wichita, Kan., and raised in New Orleans, the son of an aviation engineer. He served in the Marine Corps, and got his early radio experience with a show on Radio Guam. In one popular feature he would read “Dear John” letters from girlfriends stateside who had unceremoniously dumped their boyfriends in the service.

He later took a job replacing Alan Freed at WAKR in Akron, Ohio, and then followed Freed to New York, where Muni became one of the “Good Guys,” as WMCA-AM’s DJs were known at the time.

In 1960, Muni moved to WABC, where he was spinning records during Beatlemania.

In 1968, sick of preset pop formats and anxious to play Jimi Hendrix records, he jumped ship and took over his three-decade drive-time slot at WNEW; Muni made the station a leader in the “progressive rock” movement.

Muni became close friends with John Lennon after the former Beatle moved to New York, and whenever Lennon issued a new record, he would bring it to Muni’s show to debut. After Lennon was murdered, Muni opened each show for the rest of his career with a Beatles song.

Muni also was host to nationally syndicated shows, including “Scott Muni’s World of Rock” and the Beatles-oriented “Ticket to Ride.”

During his heyday, Muni had such celebrity status in New York that when

a man took 10 people hostage at a Midtown bank in 1975 he called Muni with his musical requests. Muni went with police to the bank and helped negotiate the gunman’s surrender. The incident was later used as the basis for the movie “Dog Day Afternoon,” according to a Q104 DJ, Ken Dashow.

Despite his friendships with rockers, Muni claimed never to have done drugs. He was, however, quite devoted to the bottle before spending time at the Betty Ford Clinic in the late 1980s. He spoke openly of his drinking, and said that he was most sorely tempted to relapse when WNEW fired him, in 1998. He continued to smoke heavily.

Although he had suffered a stroke, the cause of death was not immediately apparent. He is survived by his second wife and five children.