This project explores the obscure line between sound and music. Is there a clear distinction between consonance and dissonance? It involves programming music theory into code and using computers to procedurally generate a never-ending and constantly-changing piece. Music theory includes modes, progressions, modulations, inversions, and arpeggios. The software is programmed in Javascript, and uses a variety of computer science concepts. Modes are modeled with arrays, progressions are modeled with deterministic finite automatons, modulations are modeled with searching algorithms, and so forth.
Modes is a technical term for different types of scales. The most commonly known scales are the Major and Minor scales. Major is actually a nickname for Ionian, and Minor is actually a nickname for Aeolian. In reality, a mode or scale is just a series of half steps and whole steps on the piano. Since you can only shift the series of half steps and whole steps seven times before ending up at the same scale again, there are seven different types of modes in music theory: Ionian, Dorian, Phrygian, Lydian, Mixolydian, Aeolian, and Locrian. Each mode can be represented as an array of half steps (1) and whole steps (2) as shown below. The code can be even more succinct, having only one array and an offset value, but for code readability reasons, I chose to keep them separate.
Chord progressions is the order of chords played in a song. The roman numeral corresponds to the i-th note in a scale. A large number of songs use the I, V, vi, IV chord progression. There are general guidelines in music theory as to which chords to play after another, and it can be modeled in a diagram shown below. The diagram looks awfully similar to a computer science concept called deterministic finite automatons (DFAs) and in fact, can be modeled as one. DFAs are represented as 2D arrays in code, sort of like lookup tables. The vertical axis is which chord you are on now, and the horizontal axis is which chord you want to go to. The number corresponds to the probability of taking the path from the current chord to the next chord. The probabilities are determined based on research and quantitative analysis on how common each path is in existing music. For example, if I am currently on the IV chord, I have a 20% chance of going to the I chord, 20% chance of going to the ii chord, 50% chance of going to the V chord, and 10% chance of going to the vii chord.
