I'm not sure if this is the right place to post this, so feel free to move this or delete it.
I'm working on this application and I've run into a little roadblock. I noticed that as I play higher notes on my guitar, the sound intensity decreases (like the difference between a low E and a high E string). I noticed this before when I was learning that it would be harder to tune higher notes just because they're harder to hear.
Is there a name for this occurrence and is there some formula that I could use to normalize this, like a function where I can input a frequency and multiply the result by the intensity?