Music Arrangement Theory

Sep 04, 2021

Music arrangement theory is so important, and yet it’s hardly discussed. Even when talking about songwriting or music theory, the theory of arrangement is something that is often left out.

This is odd because basically every song ever recorded had an arrangement. Do you hear more than one instrument? Okay, then the song was arranged.

I’m going to break down how I look at an arrangement. This will guide you to understand what parts you have already and what parts you need. It will also give some insight into the purpose or job of each part. It’s my music arrangement theory.



The body is the foundation of your song. If you’re playing live with a 4-6 piece band, the parts that are played are probably the body.

The body includes the main instrument (discussed below) and often includes a lead part or two as well.

Think of the body as the most important parts of your song- the parts that people really remember or recognize as your song.

Piano, Acoustic Guitar, Drums, Bass, and an Electric Guitar playing lead/power chords would be very common examples for the body.

The body is important, because these are usually the parts you want most in the forefront. When people hear the recording, it should sound like a glorified version of the song played live, not a totally different song.

A great way to do that is to have the main instruments at the forefront. You don’t want the great solo everyone loves to be buried in the mix, you want them to go “OH YEAH!” when it comes on loud and clear in the recording.

The body has 2 more specialized parts in it as well…



The first specialized part of the body is what I call the main instrument.

There are 3 main questions to figure out what your main instrument is:

  1. If you did the song on stage with only one instrument, what instrument would it be?
  2. What instrument did you write the song with?
  3. What is the only instrument/part that plays the entire song (intro to outro)?

If the answer to all 3 is the same, it’s a safe bet that’s your main instrument.

Here are some examples of songs and what I would consider the “main” instruments in each:

  • You and Me – Lifehouse: Acoustic Guitar
  • 100 Years – Five for Fighting: Piano
  • Clocks – Coldplay: Piano
  • Uprising – Muse: Bass Guitar
  • The Diary of Jane – Breaking Benjamin: 2 Main Electric Guitars / Body of Electric Guitars

The reason it’s important to know the main instrument is this will normally be the instrument you mix first. You’re going to try to fit all the other instruments around the main instrument. The main instrument is the star of your foundation.

It’s important to note that the “main” instrument might actually be several parts. Like the “Diary of Jane” example above, there may be a couple “co-main” instruments. There really is no single part that sticks out in “Diary of Jane”, but the 2 main electric guitars working together function as the “main” part.



A lead is basically any part of the body that is primarily melodic. Any lead guitar solo would be a great example of a lead. If you count the vocal as a part of the arrangement, it technically would qualify as a lead as well.

The job of any leads is to be a melodic part of your song for someone to attach to. It’s usually a melody you could imagine someone humming or whistling along with.

The job of the leads are to add memorable, melodic parts to your song. This may be in the form of the lead vocal, lead guitar part, or something else entirely.

Leads should be tonally simple, as they will mostly be single notes at a time, rather than chords and other note combinations.



The filler parts are those that sort of “fill out” the mix. But they aren’t a part of the body- they are parts that wouldn’t normally be played live, but would help your mix really shine.

Most filler parts will be fairly simplistic- often arpeggios or other simplistic riffs. That’s because you already have the body, with its main instrument and leads, to be the stars of the show.

The filler parts’ job isn’t to stick out or to be a star. The point is to fill out the mix in the pitch ranges you may not have much in and fill in rhythmic gaps.

Filler parts are really what separate professional sounding mixes and that characteristic empty sound of a local band. A local band, if recording in a studio, may only be able to afford the time it takes to play all the parts of the body of the song. They’re paying $30/hour+, so it’s pretty understandable that they don’t want to spend another 20+ hours recording non-essential parts.

But, if you’re recording at home, there’s no reason you can’t take the extra time to record some filler parts to make your song sound that much more full and professional.

I’m a big fan of simple guitar and piano riffs and arpeggios. Sometimes I’ll do some synth or string fillers as well. It’s amazing how much more rich and full a song can sound with just a little extra time to add the filler parts.



Atmospheres are usually extremely vague and reverb-laden parts.

Think synth pads and any other vague sounds that are way in the background of your song. Ocean waves or a recording of a thunderstorm in your song would be a part of your atmospheres.

I like to think of atmospheres as a sub-category of filler. While most filler parts do still have pretty clear individual notes that stick out, atmospheres tend to be more like a bed or “atmosphere” of sound.

You might be able to pick out the individual notes of filler parts, but you probably couldn’t with atmospheres, as they are usually too far in the background and washed out with reverb to pick out anything in particular.

If you just heard the atmospheres of the song, you probably wouldn’t be able to tell what part of the song you were in. But you probably could figure that out with filler parts (and obviously could with the body).

What is the job of atmospheres? To fill the tiny cracks that even the filler parts just can’t quite fill. Also, atmospheres can do an incredible job of adding to the feel of a song. It’s amazing how much a synth pad or ocean waves can add to the tone of the whole song.

I like to think of atmospheres like one thinks of setting in most movies- really the plot and characters are the main parts of a movie, but the setting is that last part that just makes everything seem more real.

Your favorite cop show is probably your favorite because of the characters and the way they write their stories, not how much you like their home office. But yet that office makes you instantly recognize the show and gives you a feeling of home. It makes them more believable as cops. Could they change offices? Sure, but you probably wouldn’t like it. It just wouldn’t seem quite the same, even with all the characters and stories you love.

How do you think through your arrangements? What of the above concepts have you used in the past? Let us know in the comments below!

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