I have problem with understanding result of recorded audio.
I connected mic with simple non inverting op-amp, dc bias and arduino. So my signal is at 2,5V when nothing happens and changes a little bit when I generate sound. I record audio using TMRpcm and save it on sd card. Then I play it using Audacity.
Here’s my problem. When I record sound I also measure voltage changes and I can see that these changes are very small, something up to 0.5V. I can hear sounds on Audacity but they are quite weak. So I thought that I can change amplification a little to get better, stronger sound. I thought that I have 0-5V range so changes of voltage should be really few times bigger to use that range. But when I change amplification even not much, so that voltages changes are something between 0.3-1V I get something like this:
So it’s going from the bottom to the top and back. I could image that happening if voltage was changing from 0V to 5V but that was not the case.
Please help me understand why it is behaving that way and how else I can strengthen signal to get sound more distinct from noise.