I tried something like that - various white noise, audio books whose purpose is to put people to sleep (history of mathematics and I forget the other), and various types of music. They irritated rather than relaxed me. I think they might work if done very consistently but I haven't stuck with them long enough. They tend to irritate me rather than relax me. I tried pretty hard to find white noise that would work - swamp came the closest. It came much closer than rain, wind, fire, surf, crickets, and several others - lots of kinds each. Hm, I don't think I tried traffic - that might be better. I like all these sounds in real life. I think maybe the producers tried too hard to get even sound; so it sounds wrong.Has anyone tried audio relaxation apps?
Side note - I got the history of mathematics because I was actually interested in the subject rather than as a sleep aid. It was read by the actor that played Monk. He did a great job of reading it veeeerrrrryyyy slowly. My son usually listens to audio books at double speed, and he loves math - he asked for a math book for his birthday when he was six. And got one. And loved it. He's got degrees in math and engineering now. Anyway, he turned the speed way up and was very unimpressed by the historical accuracy.
Oddly, CSI Miami, the Bourne movies, and the really, really old Robin Hood tv series have often been most effective. I can't do them now, though. This house is too small to do that when other people are sleeping.