While many pop music fans can trace the spark for their interest to the moptop madness of the Beatles, the riotous anger of punk or the social realism of early hip-hop, I can largely thank one man: Casey Kasem, who died Sunday at 82.The radio DJ who counted down top-40 hits for nearly two generations — and was the voice of Shaggy on Scooby-Doo — died at a hospice in Gig Harbor, Wash. His nationally syndicated, three-hour radio show, the pioneering American Top 40, debuted in the summer of 1970, just as my 13-year-old self was developing a musical personality. Prior to that, I was happy to absorb whatever was around — Dad’s carefully tended Miles Davis, John Coltrane and Cal Tjader albums; my sisters’ stack of shiny black singles in their colorful sleeves — and hadn’t given it too much thought.But, in that year, music for me became more than just a background soundtrack for a life of baseball cards, sci-fi novels and The Brady Bunch. The Guess Who’s American Woman, Norman Greenbaum’s Spirit in the Sky, the Temptations’ Psychedelic Shack and especially the Jackson 5’s trio of awesome hits — I Want You Back, ABC and the absolutely glorious The Love You Save — proved to be siren songs to the shoals of AM radio.That’s when I stumbled across American Top 40, Kasem’s weekly countdown of the hits as compiled by Billboard magazine. The Sunday show proved to be a revelation: He aired tracks that sometimes weren’t getting airplay in L.A., where I lived, and, long before that wellspring of trivia known as the Internet was born, he offered little stories and background about each song.On the debut show, Crosby, Stills, Nash & Young’s anti-war Ohio sat comfortably next to Marvin Gaye’s seriously soulful End of Our Road, Mountain’s proto-metal Mississippi Queen, the Moody Blues’ prog-rock Questions, the Impressions’ psychedelic-soul Check Out Your Mind, Miguel Rios’ quasi-classical A Song of Joy, the Beatles’ Long and Winding Road and Elvis Presley’s The Wonder of You. A musical education in three-minute increments, this sonic smorgasbord is impossible to find on today’s equivalent to Top 40 radio.And knitting it all together with a voice radiating warmth and knowledge was Mr. Kasem, who was a weekly connection to a world that seemed both distant and fascinating.As luck and fate would have it, many years later, I ended up working at Billboard and Watermark, the company that produced American Top 40. While my lowly duties meant rarely crossing paths with Mr. Kasem, just working in the same environment was a rush.My lasting memento of that time is an autographed copy of the discs containing the very first American Top 40, broadcast July 4, 1970.Of course, by the time I got this keepsake, my musical tastes had broadened. I had deserted AM for FM, traded singles for elaborate albums with gatefold sleeves, and would later move on to CDs, downloads and streaming.But as I sit here, with news of his passing still fresh, listening to that first AT40 with both the famous (Carpenters) and forgotten (Crabby Appleton) ringing in my ears, it takes me back to those lazy post-church Sundays, ears glued to the radio, waiting for the gospel according to Kasem. And the lessons learned are as valuable today as they were 44 years ago.He would end each show with his trademark slogan: “Keep your feet on the ground and keep reaching for the stars.” Not a bad philosophy for any 13-year-old.Early years, health problems The entertainer was born Kemal Kasem on April 27, 1932, in Detroit to parents of the Druze faith.His professional breakthrough came in 1970 when he and his business partners devised a syndication arrangement offering hours of programming to stations nationwide. He became one of the highest-paid people in radio broadcasting.He retired from all his shows in 2009.His first marriage, to Linda Myers, ended in divorce. In 1980, he married Jean Thompson, an actress who played Loretta Tortelli on the sitcom Cheers. Besides his wife, survivors include three children from his first marriage, Julie, Mike and Kerri; a daughter from his second marriage, Liberty; and two grandchildren.Kasem died of complications from Lewy body dementia, a progressive brain disorder, said Danny Deraney, a publicist for his daughter, Kerri Kasem. The former disc jockey had lost the ability to walk unaided or speak without struggle.In recent months, Kasem’s degenerating condition spilled into public view because of a family rift over his care. The three children from his first marriage accused Thompson of prohibiting visits to Kasem and blocking their input on his treatment. This story contains material from The Washington Post.