STEP 5: THE BASS LINE
STEP FIVE: writing a bass line
Bass lines play a really fundamental role in most compositions. Bass instruments often help to establish the 'groove' or the rhythmic feel of the piece, highlight the harmonic structure of a piece, and play a crucial role in counterpoint.
Because lower frequency notes tend to be 'richer' and carry more audible overtones, bass lines tend to be handled slightly differently from other parts of the composition. The are several important devices that tend to be used almost exclusively for writing bass lines.
Bass lines tend to be largely based on chord tones, with an especial emphasis on the tonic and dominant (1st and 5th) notes of a chord - particularly on strong downbeats (typically 1 and 3). In many styles of music, the bass is also used to imply 'passing chords' and create forward movement from one chord to the next.
Bass parts also tend to be easier to hear than the 'inner voices' in harmonised lines, so the interplay between the bass part and the main melody line can be crucial. Polyphonic music often heavily relies on a 'conversation' between the bass line and the lead part, with other voices playing a supporting harmonic role.
You can also really spice up your chord progression by using good voice leading ideas in your bass line to create chord inversions, or imply or create other chords.
Here are some ideas you should experiment with when creating your bass line:
OSTINATO EXAMPLE 1: The Planets, "Mars" by Gustav Holst (1874 - 1934)
OSTINATO
A musical pattern that repeats itself over and over again - often whilst other things are going on over the top...
A riff is a kind of ostinato
DRONE EXAMPLE 2: Bagpipes from Baghdad by Eminem
DRONE
A drone is basically a long held note (sometimes chord), usually occuring in a bass instrument, for a long section of a piece - sometimes the whole piece...
Most bagpipe music uses a low drone tone over which melodies and ostinatos are played
ALBERTI BASS
Alberti bass Alberti bass is a kind of broken chord or arpeggiated accompaniment, where the notes of the chord are presented in the order lowest, highest, middle, highest. This pattern is then repeated. The broken chord pattern helps to create a smooth, sustained, flowing sound on the piano.
Alberti bass was often used in the Classical era and sometimes the Romantic era . It was named after composer Domenico Alberti.
Alberti bass is usually found in the left hand of pieces for keyboard instruments, especially for Mozart's Piano Pieces. However, it is also found in pieces for other instruments.
PEDAL EXAMPLE 1: Symphony No 104 D major "London" Finale by Joseph Haydn (1732 - 1809)
Listen to the cellos and basses here
PEDAL (PEDAL TONE)
Very similar to drone but generally does not last for as long. It can be drone-like but it can also just be a note that is returned to regularly...
A pedal is a single note that is held on or repeated in the bass. The chords above the bass may change, but the bass note stays the same.
CONTRARY MOTION EXAMPLE: Bourree in Em by J.S. Bach
CONTRARY MOTION
Often used in Counterpoint, Contrary motion is motion of at least two melodic lines in opposite directions. That is, when one of the lines moves up, the other line moves down.
In the example below, I've used a simple motif (and a couple of inversions) to create an effective bass line for my composition. It features an ostinato line, and the step-wise movement on beat 4 of each bar sets up the following chord change.
