Week 44: A random walk from A to D
I finally borrowed a stepladder and replaced the dead garden floodlight (which wouldn’t have been particularly useful even if it had worked) with an LED light with a motion sensor. This came in handy the very next day when I arrived home after dark and had to lock up my bike. It’s a lot easier when you can see what you’re doing, and now that the sun sets before half past four, there’s a lot of darkness to arrive home in.
The other small job I did on the house that made me feel better was to replace the sealant around the bath. It’s nice not to see mould any more.
I enjoyed working to a prompt for the Loopop contest a few weeks ago so I subscribed to the Disquiet Junto project mailing list and decided to have a go at recording another piece of music this week.
The prompt this time is Chord Channels:
The Assignment: Take two chords and connect them over time.
Step 1: The goal of this project is to produce a slow piece of music in which you move back and forth between two chords. Choose two chords that have at least one note in common.
Step 2: Map out the notes of each chord.
Step 3: Compose a piece of music in which the individual notes of each chord slowly appear and disappear, so that at any point in time part of one chord, or part of both chords, or perhaps even both chords in their entirety can be heard.
I chose Am9 and Dm9 (using voicings without 5ths) which share a single note (C) and together use all the notes in the C major chord, spread over two octaves (i.e. D F A C E G B).
I wanted to travel from Am9 to Dm9 through the 35 possible different 4-note chords that can be formed from 7 notes, swapping only one note each time. After trying various mathematical ways to generate a sequence that met these constraints (Gray codes seemed promising for a while), I ended up resorting to a brute force algorithm picking pairs at random. It produced a result so fast that I really should have tried that approach first.
I used Sonic Pi to play the sequence using my Minilogue XD (it has four voices, just enough for this) with a patch with long attack and decay and plenty of reverb, so that there’s a sense of a slow transition between each chord. I added some sounds from a field recording I made along the Thames Path in Rotherhithe a few weeks ago, and the title suggested itself naturally: “A random walk from A to D”:
I put the code both for generating the sequence and for playing the music into a gist on GitHub.