Meters and loudness
In the desktop app. The loudness readings described here belong to the desktop app and are arriving in its beta. The web studio has the level meters described under Mixer.
What they are for
Your ears adjust to whatever they are given: after a minute, any level sounds normal. Meters do not adjust. They answer two questions that ears cannot: is anything too loud for the file to hold, and how loud will this song be next to others. The master strip of the mixer shows both while the song plays: Loudness, Now, True peak and a Spectrum. Hover over any of them for what it measures.
The ideas behind this page are Loudness has a ceiling and Loudness for streaming.
Peak
The highest level the sound reaches at any instant, in decibels below the ceiling of 0 dB. Peak tells you whether the sound fits: at 0 dB it clips. It says little about how loud the sound seems, because a drum hit can have a very high peak and still be over before the ear has registered it.
True peak
A stricter peak. A digital file stores the sound as points, and when it is played back, the wave between two points can rise a little higher than either. True peak measures that. Keep it under about −1 dB on the master and the song survives being turned into an MP3 or played through a streaming service without clipping. The True peak reading on the master is the highest one since playback started.
Loudness
How loud the sound seems to a listener, averaged over time and weighted the way hearing is: a rumble at 40 Hz counts for less than a voice at 2 kHz of the same level. It is measured in LUFS. The scale works like decibels: −14 LUFS is louder than −20. The master shows two numbers. Loudness is measured from the moment playback started, so after the whole song has played it is the loudness of the song. Now is the loudness of the last three seconds: it shows which passages are the loud ones.
Two songs with the same peak can differ in loudness by a great deal, and it is loudness that the listener notices.
Streaming
Streaming services measure the loudness of each song and turn the loud ones down, so that everything plays at about the same level, around −14 LUFS. When you export a song For streaming, the studio measures it, sets it to that level with one plain change of gain, and says in the status bar what it did: turned it down, turned it up, or could not reach the level without clipping. A song far above that level gains nothing from it: it is turned down, and what remains is the flatness that the pushing caused.
This is not a rule to hit a number. It is a reason not to chase loudness: set the final level with the Limiter where the song sounds best, and let the service do the rest.
Spectrum
The master also draws which frequencies the mix is made of: low at the left, high at the right, louder is taller. It is the same picture the EQ draws for one track, here for the whole song. A mix with a hole or a hill in it shows here before you can name it by ear; compare the shape with a song you like played through the same master.
Louder sounds better
Of two versions of the same sound, the ear prefers the louder one, even when the difference is too small to notice as loudness: it seems clearer, fuller, closer. This fools everyone, and it is why a device that only made the sound louder seems to have improved it. Compare with a device on and off, or your song with someone else’s, only at the same loudness.
Mono
How well the song survives being played from one speaker. When the left and right sides agree, mono playback loses nothing. When they disagree strongly, parts of the song cancel and disappear on a phone or a single speaker. The master has no reading for this yet. To check, put a Utility last in the master’s chain and switch Mono on for a moment: whatever disappears has two sides that cancel, and Flip phase on one of the tracks involved is the usual fix.