frequency

The frequency property defines the pitch of a note in Hertz (Hz).

Default Value

new Fraction(440)  // A4 (concert pitch)

Expression Examples

Fixed Frequency

new Fraction(440)   // A4
new Fraction(261)   // ~C4
new Fraction(880)   // A5

Relative to BaseNote

// Same as BaseNote
module.baseNote.getVariable('frequency')

// Perfect fifth above (3:2 ratio)
module.baseNote.getVariable('frequency').mul(new Fraction(3, 2))

// Octave above (2:1 ratio)
module.baseNote.getVariable('frequency').mul(new Fraction(2))

// Perfect fourth below
module.baseNote.getVariable('frequency').div(new Fraction(4, 3))

Relative to Another Note

// Major third above Note 1
module.getNoteById(1).getVariable('frequency').mul(new Fraction(5, 4))

// Octave below Note 3
module.getNoteById(3).getVariable('frequency').div(new Fraction(2))

TET (Equal Temperament)

// 12-TET semitone
module.baseNote.getVariable('frequency')
  .mul(new Fraction(2).pow(new Fraction(1, 12)))

// 12-TET major third (4 semitones)
module.baseNote.getVariable('frequency')
  .mul(new Fraction(2).pow(new Fraction(4, 12)))

// 19-TET step
module.baseNote.getVariable('frequency')
  .mul(new Fraction(2).pow(new Fraction(1, 19)))

Irrational Frequencies

TET frequencies are irrational and display with the ≈ prefix. RMT Compose preserves their algebraic form using SymbolicPower.

Common Just Intonation Ratios

Interval	Ratio	Expression
Unison	1/1	new Fraction(1)
Minor second	16/15	new Fraction(16, 15)
Major second	9/8	new Fraction(9, 8)
Minor third	6/5	new Fraction(6, 5)
Major third	5/4	new Fraction(5, 4)
Perfect fourth	4/3	new Fraction(4, 3)
Tritone	45/32	new Fraction(45, 32)
Perfect fifth	3/2	new Fraction(3, 2)
Minor sixth	8/5	new Fraction(8, 5)
Major sixth	5/3	new Fraction(5, 3)
Minor seventh	9/5	new Fraction(9, 5)
Major seventh	15/8	new Fraction(15, 8)
Octave	2/1	new Fraction(2)

Visualization

• Vertical position on the workspace represents frequency
• Higher frequencies appear higher on screen
• The Y-axis uses logarithmic scaling: log2(baseFreq / freq) * 100
• Dashed lines indicate octave boundaries

Audio Playback

During playback, the frequency value (converted to a JavaScript number) is used to set the oscillator frequency. For irrational frequencies (TET), the floating-point approximation is used.

Dependencies

When a note's frequency references another note, a dependency is created:

// Note 2 depends on Note 1's frequency
module.getNoteById(1).getVariable('frequency').mul(new Fraction(3, 2))

Changing Note 1's frequency will automatically update Note 2.

See Also

• Pure Ratios - Just intonation theory
• Equal Temperament - TET systems
• Expression Syntax - Full syntax reference