Audio Codec Problem

Hy. I have a problem, and i can't seem to fix it. I've made a digital recorder. I record my voice, store it on the sram, and later, i'm playing it.

It works, but with a lot of noise on the background.

I'm playing my voice in a loop, and sometimes i hear it just fine, but most of the times it si drown by noise. I tried everything, but i can't seem to find the problem.

Can you give me an advice? Mabe an ideea? Thanks.