For some phones at least it is not digital clipping, but speaker distorting the sound. A simple test would be to attach speakers or headphones. If it sounds bad

For some phones at least it is not digital clipping, but speaker distorting the sound. A simple test would be to attach speakers or headphones. If it sounds bad both on internal speaker and external speakers, then, yeah, it's digital clipping. If only the internal speaker, then it's simply too weak to handle the signal, or phone chassis starting to resonate or something like that.