I am building a small soundboard for my project using an Arduino Nano, [https://a.co/d/hvWRh9u](https://Adafruit Soundboard), and an [https://a.co/d/76T0795](Adafruit Amp). It works fine except a very faint local radio station is constantly playing in the background as long as it is powered on. It's pretty cool, but it's not really the project I was going for and my concern is that this project will be running on battery power and I don't want the speakers constantly playing noise, even if you can barely hear it. After I play a sound from my soundboard there is a loud high pitched tone that emits from the speaker along with the sounds (and radio) until the project is turned off. I don't know if this is related to the interference but if anyone knows a fix for that as well that'd be nice.
Everything is powered by a single USB (both laptop and battery bank power had interference) plugged into the arduino nano. I am using the ground pins, 5v pin, and some digital output (constant highs and lows) for 5v and gnd respectively since I ran out of dedicated 5v and ground pins to use. I read in other forums that it could be caused by poor grounding acting as an antenna or something. I'm not sure how to determine if my grounding is poor however.
If I skip the amp entirely and run from the soundboard to my speakers, I dont hear any interference, but I'm not sure if that means the interference is coming from the amp since it could just be quiet enough without the amp that I don't hear it. If I turn up the volume potentiometer on the amp, the radio volume also increases. I tried holding some foil around each of my components to see if it would shield it but pretty much nothing changed. I dont know if that actually works but thought I'd give it a shot.