When people hire me to mix their songs, I frequently come across situations where we are not using the same terminology for the sources clients are giving me to work from. Yes, sometimes one word can mean several different things, but generally the consensus among audio professionals is fairly clear. So, I started making a list of terms to help us all out.

Song

A piece of music or structured sound. A recording can represent the Song, and the Song can come to life via the recording process, but the Song is not specifically always the recording.

Session

In a digital audio workstation (DAW), a Session contains all of the elements associated with a recording project. These can include audio files, mixer settings, routing, automation, edits, and more. A DAW Session encompasses all assets needed to open, play, and edit the song. If you want to share a Session with another engineer, you must include the Session file and the underlying audio files, backup Sessions, and other housekeeping items. Most engineers create a different Session for each song; but more than one song may live in the same Session, especially during principal tracking or capturing of live performances. A DAW Session is distinct from a recording Session, which generally refers to the place and time music is tracked. This is particularly important when hiring a mixing engineer. If you say, “All these songs to mix are from the same Session,” this informs the engineer that most of the basic instruments will have similar sounds and track counts among the batch of songs. This is important information to impart because it could have been that all the songs were in the same DAW Session, but captured on different days in totally contrasting ways!

Track

An audio file that generally runs the length (or part of the length) of a song, even if it is not always generating sound. Note that a collection of MIDI notes, or MIDI with a virtual instrument, can also be a Track as it is a linear representation of something that can generate sound as the session plays. Usually this is mono or stereo, though it could be more if one was working in immersive audio.

Clip

A portion of recorded sound that is usually organized or contained within a track. A Clip could be a whole track, or a track can be made up of many Clips. Clips are found in computer-based recordings, but not on analog tape or other linear systems where you only have tracks. Some DAWs use different terms for Clips, such as objects, snippets, regions, and so on.

Routing Terminology

Most DAWs emulate the console and tape machine paradigm. The edit window shows the tracks and permits editing. The mix window shows channels and mimics a large format console. One of the most powerful features of a console is the ability to route audio tracks numerous ways, depending on need. DAWs can route audio like a console (and more), but it can be less obvious without years of experience. The following are the main tasks and terms related to routing.

Bus

A Bus is basically a channel that can receive audio signals from other channels via routing. This allows for combining multiple tracks in one place, either for easier control of levels (“Turn up the drum Bus!”) or to apply shared processing to multiple tracks in one swoop, like compressing all the backing vocals or such.

Aux

Thanks to digital DAW recording, this is where it gets messy. On an analog console, an Aux (auxiliary) send is generally used to send signals from a track to some type of processing (often reverbs or delays) that can be blended back into the mix via an Aux return, channel, or even a bus insert point. One can also use an Aux to feed parallel compression, like I do for analog drum mixing. But when I mix in the box with Pro Tools, what I set up to use as buses are actually called Aux Inputs. It all works the same – and the flexibility of digital recording allows for this – but on a console it’s delineated, although we can use the routing to similar effect.

Aux Return

This is simply a channel that has been assigned for a return path; usually associated with a corresponding aux input, but not at all tethered to it. On a console, this path usually has little processing power but maybe has some bus assignment abilities. In a DAW it can be used as a bus (see above), but it is usually called an aux input.

Insert

An Insert point is simply a routing point within a channel, bus, or aux return/input where the signal can be snagged for processing and returned. An example would be inserting a compressor or EQ on a channel. Keep in mind that knowing where this Insert actually lies in the signal path is important. Is it pre or post fader? Before or after the EQ? Also, don’t forget to study gain staging!

Submix

A Submix is a channel that combines a group of audio signals that require similar processing and/or level control. Think of a Submix as a shipping department where tracks are gathered and processed before they are sent to their destination. Submixes are useful for being able to control several tracks with one fader, but they can do other tasks, including going into another Submix.

Stem

There are many instances when it can be useful to have instrument and/or vocal elements separated into constituent submixes. In a standard rock song, there could be drums, guitars, bass, and vocals. Rendering each of these elements into their own files creates a Stem. In theory, playing all the Stems together will sound just like the entire mix. It is worth noting that Stems do not need to be stereo. A Stem could be a single track with processing added, like a lead vocal with compression, EQ, and/or reverb. Many times, my clients refer to their tracks as Stems. This leads to confusion, as I have to ask if they are sending me submixed or combined elements of the song, and if it might be better to send me the raw individual tracks. Usually, they are simply using the wrong words.

Channel

A path for audio to be routed through, for summing and/or assignment. Think of an old school analog console, where some Channels have instruments, and others have effects returns. A Channel itself does not possess its own audio; rather it is simply a conduit for audio to come through. This is important to understand, as a Channel could be a pathway for many tracks and even stems.

Demo

A version of a song that is generally not related, recording-wise, to the desired final mix. By most parlance, a rough mix is not a Demo, though I see some pros use “Demo” to denote a rough mix, at times.

Rough Mix

A Rough Mix of a song that has been determined to not be the final mix. This can possibly be done just to reference what was recorded during the tracking session, or it could be a nearly finished mix that still needs some work. Sometimes Rough Mixes end up as final mixes. You never know!

Mix

An iteration of a song created from mixing tracks or stems together, likely via channels.

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