Loudness Matching lets listeners compare your A/B (or A/B/C) versions at equal perceived loudness — so the comparison is about tone and quality, not just "the louder one sounds better."
How it works: SoundToggle measures the integrated loudness (LUFS) of each version and applies a playback-only volume trim to bring louder versions down to match the quietest one. This is playback gain only — your audio files are never modified, re-rendered, or re-uploaded.
You decide how it behaves (all plans): On the Edit Project page, open the Loudness Matching section and pick one of three modes for your public player:
- Off — versions play at their natural levels. Nothing extra appears on the player.
- Locked — every listener hears your matched levels, with no control on the player. Optionally show a "Loudness matched" label so listeners know the comparison is level-matched.
- Listener's choice — the player shows a "Match loudness" button next to the quality badge, and you choose whether it starts matched. Listeners can flip it at any time, and the match holds through the crossfade when toggling between versions.
If you haven't measured or set trims, the player measures loudness right in the listener's browser (about a second) the first time matching turns on.
Measurement & fine-tuning (Pro and above):
- Click "Measure & match (LUFS)" to automatically measure each version and see the results (e.g., "First: −14.1 LUFS · Second: −7.8 LUFS").
- Adjust the per-version trim sliders manually (−12 dB to +6 dB) — these work even without measuring.
- Reset to clear all loudness settings back to none.
Attenuate-only matching: Automatic measurement only ever turns versions down to match the quietest one — it never boosts a version above 0 dB. Manual sliders allow a small boost (up to +6 dB) but show a "may clip" warning since boosting can push a track into clipping.
Loudness Matching is only available for A/B comparisons (not standard single-audio players).