If a song is in a certain key, can you add an instrument or vocal to the song / track as long as they are in the same scale of that key. So for example, if a song is in key D major, you can add any instrument/vocal as long as the key is in the D major scale, so E minor, B minor, G Major, A Major, etc, etc.

I'm sure this is an easy question, but I'm very new to music and scales.


  • 2
    Welcome! Basically, yes, when a song is in a certain key, which most are, then you can add a track, or play along with it, in that key. That will sound best. If what you're saying is that any track in a particular key will only contain those chords you mention, then not necessarily. There are many questions asked here about that subject, and so many are based on the premise that only diatonic notes and chords must be used in a song.If that's where you're coming from, then the answer's no! You're also confusing chords and scales. They're related, but different.
    – Tim
    Commented Apr 24, 2020 at 8:23
  • If it is a non-transposing instrument and you don't mind some weird sounds and strange voice leading: yes. Commented Apr 24, 2020 at 8:54
  • Have you tried it? Commented Apr 24, 2020 at 10:03
  • thirds and sixths: The Musical Dilettante: A Treatise on Composition by J. F. Daube (s. my answer ...) Commented Apr 24, 2020 at 13:22

4 Answers 4


You can add whatever you want, but it might not sound the way you expect it to.

I assume that the effect you want is for it to sound "consonant" (ie no dissonances) so that it sounds pleasing to the ear following our Western popular music convention.

In that case, it's not just about the key: you also need to follow the same tempo and the same chord progression.

Following your D major example. If you add a track/melody that's playing on the notes of a D major chord while your song is playing an A7 chord, the tension effect might be broken. Conversely, if your new track is playing on an A7 chord when your song playing over a D major you might have a dissonant effect.

Also, the tempo. If the tempo of the new tracks are mis-aligned, you will get an unpleaseant "off-tempo" feeling.

Many accomplished musicians, especially coming from a jazz background, can easily improvise a new tune ontop of an existing chord progression. However, this takes either some good musical hearing or a fair amount of training.


The instrument should not matter as long as it is tuned to western scales. The whole concept of key as we use it typically refers to the 12 TET chromatic tuning in this day and age. So as long as the instrument is capable of playing or being tuned in this way and the player knows how to play it then yes. A counter example might be a Turkish instrument called the Saz. This is a guitar like instrument that has 1/4 tone frets on it. They even make modern electric versions of it. So if you invited a Turkish Saz player to lay down tracks there may be some conflict, or it may sound very cool. Another counter example might be fret less instruments where you can adjust your fingering and play in Just tuning rather than equal tempered.

The quality of the tone is related to the instrument and some instruments are better suited for certain ranges (octaves). But this is not an issue of key signature and being in tune but rather of orchestration and having the whole band sound good together. For example composers and arrangers (producers too) invest time in deciding which instruments should play which parts of a score. Even in a small rock band guitar, bass, and keyboards can clash when playing in key if they the mix of ranges is not diverse, i.e. no contrast. Even when everyone is playing in the same key it is no guarantee that they will sound good together.


To make your first experience of adding a second instrument to any melody you can play or write a seconde voice following the melody in thirds or sixths without any problem. It will sound a little bit more classical and folk music (school music) than pop or rock style: e.g. Silent Night, O how joyfully, Panis Angelicus, or keep the second voice on the same tone and skip to the next chord like Something stupid (Frank and Nancy Sinatra).

Zauberflöte, Mozart :

Panis Angelicus, César Franck

Don't cry for me Argentina:

Swiss and Austria folk music:

or if you like this (old German hits:)

or find a second voice to this song:


If a song is in a certain key, can you add an instrument or vocal to the song / track as long as they are in the same scale of that key?

If I understand this question correctly, the answer is no.

It seems that you are asking whether any two tracks will necessarily sound good together if they are in the same key. Being in the same key is only a very small element out of the many that determine whether two parts fit together, whether they are melodies or chord progressions.

It seems like you might be under the impression that every pitch used in a given key sounds harmonious when combined with any other pitch from that same key, but that is not the case. Two arbitrarily chosen pitches from the same key might therefore clash with one another. Composers writing harmony parts know which notes to choose to avoid such clashes, or even to capitalize on such clashes to create dissonant tension that resolves to consonance, but if you pick just any other melody written in the same key it is possible that the dissonant moments will occur randomly, without structure, resulting in an incoherent mess.

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