Streaming services use volume normalization to create a balanced listening experience across playlists and albums. Services like Spotify, Tidal and Apple Music determine an average loudness value for singles, EPs & LPs using a loudness measurement called LUFS. The song, EP or LP's loudness value is used to normalize playback volume to a target level set by the streaming service. The Audio Engineering Society suggests a streaming target level of -16LUFS, however, most streaming services use a louder target level between -13 and -16LUFS. Streaming service's target levels are much lower in volume than master levels preferred by modern artists, producers and engineers. Because of the difference between master levels and streaming service target levels, the louder a master recording is made, the more streaming services will turn down the recording to match their target level. For example, if you master an album to -8LUFS (loud) and submit the files to Spotify, they will turn down the songs playback volume 6dB to match their target volume of -14LUFS.
Streaming Service Target Volumes:
- Apple Music (soundcheck on):
Mastering Levels and Streaming Service Target Volumes:
Below are five different masters of a single song at a different loudness levels (-8LUFS, -10LUFS, -12LUFS, -14LUFS and -16LUFS). The target playback level in the below example is -14LUFS (Spotify & Tidal). Loud master recordings (pink, orange, yellow) are turned down to the streaming service's target volume. Lower level masters are not turned down as much and provide for a greater peak to loudness ratio than albums that are mastered at loud volumes. in effect, the louder you master your album, the lower your peak to loudness ratio.
Test Files Submitted to Streaming Services:
To illustrate the playback volume manipulation performed by streaming services I have submitted test files of master levels to streaming services. Each file consists of an identical sequences of pink noise calibrated to specific loudness levels. The five songs were submitted as "singles" to streaming services so that each track's volume is assessed individually, and not as an average for the entire EP or LP. Some streaming services have an "album mode" which normalizes the entire album's average volume to the streaming service's target volume and maintains the individual level differences between tracks set by the mastering engineer. The below test files were submitted as singles to avoid the album mode loudness averaging. This simulates what a song would do when it is added to a playlist. You can download the 16 bit, 44.1kHz test files below and the AAC files here.
Test File Info:
- "8 Times" -8LUFS, -1.9dBTP
- "10 Shoes" -10LUFS, -4dBTP
- "12 Dozen" -12LUFS, -5.9dBTP
- "14 Team" -14LUFS, -7.9dBTP
- "16 Ounces" -16LUFS, -9.9dBTP
Streaming Services & Normalized Playback Volume:
Click the below links to open in-app playlists of the above test files.
The track "8 Times" is mastered 8 dB louder than "16 Ounces", but both tracks play back at a very similar perceived volume on all Spotify, Tidal and Apple Music.
As you can hear in the above playlists, louder masters do not create a louder playback experience for the listener. The use of playback normalization algorithms eliminate the need for projects to be mastered at extremely high levels as they were in the early aughts. Songs mastered at different volume levels are streamed at almost identical playback levels. Even though each streaming services has a different approach to loudness normalization, they all use a target level far below the master volume preferred by many modern artists, producers & engineers. By mastering records closer to streaming service's target playback level, you will achieve a similar perceived playback volume, but gain the benefit of additional transient detail in the lower level master. As you can see in the below example, a song mastered closer to the playback level of a streaming service will provide additional transient detail (peak to loudness ratio) over a loud master, but will stream at a similiar playback level. Obviously, music is not made by measurement and some forms of music simply sound better with more compression and limiting in the master recordings, while other styles of music will benefit from a more gentle approach. You should work with your mastering engineer to determine an appropriate target level that suits your particular project and genre.
Unfortunately, not all platforms have adopted playback normalization into their listening experience. Soundcloud and Bandcamp do not perform volume normalization. Soundcloud is said to have plans to adopt loudness normalization, but not Bandcamp.