The bassline is one of the most essential aspects of harmony, and it can be one of the most fun to write and work with. Laying down a fun bassline can sometimes come naturally, but it is important to understand the bassline’s role and function and why those things sound good.
Function and Role of the Bassline
Traditionally the bassline is the foundation that the rest of the harmony is built on. The most basic function of it is to play the root of the given chord. For example, if it is a D major chord, the bass would be playing D. If it is E major, it would play E, and if it is A minor, the bass would play A.
This serves to anchor the chord while the other parts fill out the rest. However, the bassline is free to move more independently, which keeps things interesting.
While the traditional role of the bass is to play the root note, it can do many other things. Chord inversions are where the bass is playing a chord tone other than the root note. Say you have a D major chord, the notes of the chord are D, F#, and A. Instead of the bass playing just the root, D, it could be playing F# or A.
It is commonplace for the basslines to include a lot of roots and 5ths in songs produced today. That would be D and A in the example of the D major chord, so if ever in doubt, keep that in mind.
Non-Chord Tones in the Bassline
Not every note the bassline plays will be in the indicated chord; these are called non-chord tones. In the example of a D major chord, any note that is not a D, F#, or A is a non-chord tone. There are a few different kinds of non-chord tones that can be applied to make a bassline more interesting.
The first non-chord tone we’ll cover is a passing tone. Passing tones act as a bridge between two notes in the bassline. Say you are playing a D major chord followed by a B minor chord. The bassline could simply play the roots: D then B.
However, it could use the C# in between them. In this case, it would go D to C# during the D major chord, and then B when in the B minor chord.
A neighbor tone is a simple but effective non-chord tone for basslines. Say a song is playing a D major chord, the bass part could play just a D over and over, but it could also move up or down a note and back in between.
A pedal tone is super fun and super easy to implement. It is when the bassline plays the same note over and over while the chords change. While the other instruments and parts change chords, the bassline repeatedly holds down the same note.
A great example of this is the opening of the song “Kashmir” by Led Zeppelin.
While the role of the bassline in harmony may seem simple at first, it can branch out into a lot of fun ideas. This does not mean that complex is always better, however, as there will always be a right time and place to employ each of these concepts in your basslines. It can be the rock that keeps a song grounded, so if you want the song to be less so, make your bassline more sporadic. As you grapple with these ideas and get a feel for them, you’ll be able to figure out the other great ways to relate the bassline to harmony.
About the Writer
Nick K. is an instrumentalist, performer, songwriter, arranger, and producer from the Philadelphia area. With a degree in Arts in Music from Columbia College Chicago, Nick enjoys playing the guitar and bass guitar and is currently recording and producing an album.