Thanks everyone, I've implemented the caps and the single supply and it's certainly helped reducing the noise value, although there is still prevalent noise that seems to partially be from the analog pin itself.
In the pictures below:
'noise1' is the plotter with A0 just connects to a voltage divider formed between 5+ and GND, nothing else.
'noise2 & 4' are with A0 connected like the circuit above, with all the new addons, without any sounds, with and without C1 respectively. 'noise4' baudrate is 5 times 'noise2'.
'noise3' has the same setup as 'noise2', but with 'Demons' from Imagine Dragons blasting from my phone about 20cm away from mic, at max volume with speaker pointed directly at the mic. Point the speaker backwards and the plotter looks like 'noise2 & 4'.
Is there a way to reduce this problem? I haven't seen one searching google yet, and I doubt there is. I can work with it anyways, so I'm not too concerned.
