I can totally hear a pattern overlaying the white noise sound in my kid’s white noise machine. The sound of the pattern varies based on the level of battery charge, as far as I can tell. I thought it was some kind of unintended noise coming from the circuitry (like maybe bad caps). Given that the underlying white noise sound doesn’t seem to vary based on the state of charge, I am still not sure that the sample length is what causes the pattern, but now you’ve got me super curious to tear the damn thing apart to test the caps.