[UPDATE Nov 2016: TIDAL now also use normalization, and Soundcloud say it’s “on the list”]
[UPDATE July 2017: Spotify recently lowered their reference level to -14 LUFS]
We know now that all the major music streaming services are using loudness normalization – higher level songs are turned down, aiming for a “target” loudness, which is different for every service.
Loud songs are turned down, quiet songs may be turned up on some services – IF there’s enough peak headroom.
And because the target level for some platforms is pretty loud, that’s a very significant “IF”.
YouTube and TIDAL don’t turn quieter songs up at all. And even on services that do, when there isn’t enough headroom to lift the level up without clipping, your music either won’t get turned up and will sound quieter than everything else as a result, or it may have extra peak limiting applied to get it up to the target level. Which may or may not sound good.
None of these is an ideal situation !
How loud is loud enough, and how loud is too loud ?
The answer is… it depends.