I’ve come across this in threesomes. I am the third with a married couple.
Before we started they told me how they liked to handle pics and videos. At that point it was up to me to agree or not. I certainly didn’t want my face exposed. Their method insured that it wouldn’t be.
The husband took pics and vids from behind of his wife riding me. The audio was fun as he cheered her on to give me a good fucking.
His favorite was me doing her missionary. He couldn’t get any closer to us as he did a vid of my cock going in and out of her pussy.
The most fun for me was finishing her doggy. He took a video behind me ramming my cock into her pussy. And this time, without using my name, he kept cheering me onto give it to her good and fill her up with my seed.
In one of these encounters the husband wanted to blow me. And the wife took a video showing his face but just my cock. And she made me laugh as she kept shouting at him to “suck that cock, you know you love it”
It depends. It’s something that works a bit differently for everyone. For me it’s sounds like clicking and slurping. Especially erotic sounds like oral sex. For others it’s less erotic.
YouTube has a lot of the non-erotic asmr vids. They’re best experienced with a headset for proper stereo effect.
For erotic there’s https://eroasmr.com/ but I generally use general videos which do have good audio