Streaming platforms turn playback up or down so listeners are not constantly reaching for the volume control.
Definition
Playback level is adjusted after delivery
Loudness normalization measures a track and changes playback gain so it lands near the platform's target. It does not remix or remaster the file; it changes how loud the listener hears it.
A very loud master may be turned down. A quiet master may be turned up if the platform has enough headroom to do it safely.
Impact
Hotter is not always bigger
If two masters are normalized to similar playback loudness, the crushed one may lose punch without sounding louder. The extra limiting becomes a tone choice, not a guaranteed volume advantage.
This is why loudness targets should be judged with genre, dynamics, and distortion in mind instead of chasing one universal number.
Check
Master for playback, not just export
Compare integrated LUFS, true peak, and reference tracks before final delivery. The goal is a master that survives normalization and still feels intentional.
Meter Core gives you the loudness and ceiling context needed to make that tradeoff before upload.