Stem (audio)

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A stem in audio is a group of sounds mixed together as one unit. Stems can be mono, stereo, or spread across many tracks for surround sound. They help manage complex mixes by keeping related sounds together.

The idea comes from early film sound. In the 1929 German film Das Land ohne Frauen, dialogue was kept separate from music and effects. In film mixing, dialog, music, and effects are often kept as separate stems (D-M-E). This makes it easy to replace dialogue for other languages or adjust music and effects for different playback systems. The non-dialog stems can be sent to another facility for foreign dubbing (M&E). A dialog stem can be used on its own to assemble trailers.

In music and live sound, stems are groups of similar sounds (for example, all strings or all drums). When many people work on a project, stems help the final mixer. Stems can be mixed later to create the finished recording, or mixed at the same time during a live show.

Stems are also useful in studios so performers can adjust their own monitor mix by changing levels of other tracks. Listeners can even use stems to create their own mix of a song. A common license is the Premium Stem License, which provides instrumental stems so artists can re-mix the track. If a track isn’t provided as stems, software can separate it into stems (vocals, instruments, drums) for remixing, making instrumentals, or creating acapella versions.

DJs use stems to mix different elements live. Some DJ software can do real-time stem separation, but this feature isn’t widely available yet. In some cases hardware with stem features has been upgraded or replaced with traditional stem mixing.

Streaming services have varying rules. Tidal briefly paused stem separation for DJs in 2023 and later resumed it with an extra fee. Spotify and Apple Music do not allow stem separation. Beatport supports stem separation on compatible software. Popular DJ programs that support stems include Rekordbox, Serato DJ, VirtualDJ, Djay, Traktor, and Engine DJ.