Streaming services determine an average loudness value for singles, EPs & LPs. The loudness value of the recording is used to normalize playback volume to a target level set by the streaming service. Volume normalization is achieved by turning up or down the recording's playback level in order to match the target level. The Audio Engineering Society suggests a streaming target level of -16LUFS, however, prominent streaming services use a target level between -13 and -16LUFS. However, target levels for streaming services are are much lower in volume than the master levels preferred by many modern artists, producers and engineers. To this effect, the louder an engineer masters their project, the more a 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 its 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 waveforms in the black boxes represent the five sets of masters. The target playback level in the below example is -14LUFS (Spotify & Tidal). Loud master recordings are attenuated (turned down) to the streaming service's target volume. Quieter masters are not attenuated as much and provide for a greater peak to loudness ratio. Conversely, the louder you master you album, the lower your peak to loudness ratio will be.
Test Files Submitted to Streaming Services:
The below loudness test files were submitted to all streaming services. Each file consists of identical sequences of pink noise calibrated to specific loudness level. 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 measurement. If the files were submitted as an EP, the differences in level between tracks would be maintained during playback. You can download the 16 bit, 44.1kHz test files below and the AAC files here.
- "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 streaming services. By mastering at levels closer to the normalized playback volume, your music will take advantage of the full dynamic range of the playback medium at a similar perceived playback volume. The difference between average volume and peak information is measured as a peak to loudness ratio (PLR) or crest factor.
The use of playback normalization algorithms are eliminating the need for projects to be mastered at extremely high levels. Songs mastered at vastly different volume levels are streamed at almost identical playback levels. Even though each streaming service 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. With that said, I believe some styles of music can benefit from well tuned compression and limiting, but there is a clear point of diminished returns. As you can see in the below picture, a song mastered closer to the playback level of a streaming service will provide additional transient detail over a loud master, but will stream at an identical or extremely close playback level. You should work with your mastering engineer to create a final master that both takes into consideration the loudness normalization of streaming services and the artistic and sonic vision you have for your project.
Unfortunately, not all services have adopted playback normalization, but Soundcloud is expected to adopt a loudness normalization in the near future.
Streaming Services That Do Not Normalize Volume: