There are two different sorts of compression being discussed here. Digital sound (PCM) is not inherently compressed*. Much digitally recorded sound may be compressed by sound engineers (dynamic range etc.) Digital sound files and streams may be compressed to make them smaller, which may (mp3) or may not (flac) be lossy - i.e. discard some of the sound.

*Assuming a theoretically 'ideal' microphone and electonics.