One of the things that really stood out for me in Quentin Tarantino's Once Upon a Time in Hollywood is how he captured the sounds of the late 1960s. Everything from AM car radio speakers, to the way people talked, to KHJ Boss Radio disc jockey airchecks, to TV interstitials, to the rumble of gas-guzzling car engines, added to the perfect visuals of 1969 Los Angeles. In this podcast, Tarantino talks about how he got the sounds for the movie. One of his main sources of information was fan recordings of KHJ radio from the late 1960s.
Here is a great "rapid-fire salute to 93/KHJ Boss Radio in Los Angeles utilizing jingles and other production elements."
And ere's Alison Martino's article for Los Angeles Magazine, "KHJ, L.A.’s Coolest AM Radio Station, Is Basically a Background Actor in 'Once Upon a Time in Hollywood'”