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Temper.js

A lightweight music theory library for tuning the web audio api.

temper.js' goal is to provide an easy way to convert pitch names to frequencies (and vice versa) in a variety of 12 step temperaments. It also provides easy access to intervals, chords and scales for pitch comparisons to aid in researching the science of music.

Installation & Simple Usage

First off, get temper.js into your webpage:

bower install temper  
<script src='bower_componentes/temper/temper.min.js'></script>

or into your node app:

npm install temper
var temper = require('temper.js');

Next, create a temper object:

var a440 = temper('A4');          // creates an object with "A4" as the tonic
a440.interval('m3');              // adds an interval (minor 3rd) to the object
a440.interval().name;             // returns "C5"
a440.interval().frequency;        // returns 523.251
a440.temperament('Pythagorean');  // changes the object's tuning system
a440.interval().frequency;        // returns 521.48
a440.scale('Whole Tone');         // adds a scale (Whole Tone) to the object
a440.scale().midiNotes;           // returns [69, 71, 73, 75, 77, 79, 81]
a440.scale().names;               // returns ["A4", "B4", "C#5", "D#5", "F5", "G5", "A5"]

Documentation

Table of Contents

• Notes
• Intervals
• Chords & Scales
• Temperaments
• Temper
• Helper Functions

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Notes / Tonics

Constructor

When called with arguments, creates or changes a temper object's tonic (base note).

temper.note([noteName or frequency])
temper.tonic([noteName or frequency])

The argument is the note wanted for the tonic of the temper object.

• noteName String
  Made up of a note name and an octave, e.g. 'A4' or 'E#5'

• frequency Number
  The desired frequency in hertz, e.g. 440 or 261.252

Attributes

When accessed without arguments, provides access to the tonic's attributes.

temper.note().attributeName
temper.tonic().attributeName

• name returns String
  The full name of the note (letter + accidental + octave)

• frequency returns Number
  The frequency of the note (in hertz) in the current temperament

• octave returns Number
  The octave of the note

• letter returns String The note's name without the octave

• accidental returns String
  The note's sharp (#) or flat (b) modifier (if any)

• midiNote returns Number.
  The standard midi note

Methods

These can be called on a newly constructed or pre-existing temper object with chaining.

temper.note().play()
temper.tonic().play()

• play([length])
  Simple 'synth' sound playing back the current tonic. Takes a single, optional argument of length (in seconds).

• pluck([length])
  Simple 'string pluck' sound playing back the current tonic. Takes a single, optional argument of length (in seconds).

Examples

var a440 = temper.note(440);

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Intervals

Constructor

When called with arguments, creates or changes a temper object's interval above or below the tonic.
Requires a tonic to be set.

temper.interval([noteName or frequency or intervalName], [direction], [octaveOffset])

The first argument is the note wanted for the interval of the temper object.

• noteName String
  Made up of a note name and an octave, e.g. 'A5' or 'Gb7'

• frequency Number
  The interval's desired frequency in hertz, e.g. 880 or 123.456

• intervalName String
  A named interval size, e.g. 'P5' or 'm2'
  Show a list of available options

• direction String Either 'up' or 'down'
  When used in conjunction with an intervalName, tells whether to make the interval above or below the tonic

• octaveOffset Number
  How many octaves the interval should span, defaults to 0

Attributes

When accessed without arguments, provides access to the intervals's attributes.

temper.interval().attributeName

• name returns String
  The full name of the interval (letter + accidental + octave)

• frequency returns Number
  The frequency of the note (in hertz) in the current temperament

• octave returns Number
  The octave of the note

• letter returns String The note's name without the octave

• accidental returns String
  The note's sharp (#) or flat (b) modifier (if any)

• midiNote returns Number.
  The standard midi note

• intervalName returns String
  The name of the interval size

• direction returns String
  The direction, 'up' or 'down', of the interval

• frequencies returns Array
  The interval and the tonic's frequencies

• midiNotes returns Array
  The interval and the tonic's standard midi notes

• names returns Array
  The interval and the tonic's note names

Methods

These can be called on a newly constructed or pre-existing temper object with chaining.

temper.note().play()
temper.tonic().play()

• play([length])
  Simple 'synth' sound playing back the current tonic. Takes a single, optional argument of length (in seconds).

• pluck([length])
  Simple 'string pluck' sound playing back the current tonic. Takes a single, optional argument of length (in seconds).

Examples

var a440 = temper.note(440);

Chords & Scales

Temperaments

Temper & Helper Functions

Calling temper() as a method provides a shorthand for creating a tonic, with some additional, advanced functionality.

Constructor

When called with arguments, creates a temper object and sets it's tonic.

temper(noteName or frequency, [tuningFrequency], [temperament])

The first argument is the note wanted for the tonic of the temper object.

• noteName String
  Made up of a note name and an octave, e.g. 'A4' or 'E#5'

• frequency Number
  The desired frequency in hertz, e.g. 440 or 261.252

Optional arguments include:

• tuningFrequency Number
  The pitch the system tunes to, defaults to 440

• temperament String
  The name of the desired tuning system*, defaults to 'Equal'

Attributes

same as temper.note()

Methods

In addition to play() and pluck() that are found on temper.note(), temper also has the following helper functions that are not accessed through the constructor.

• temper.intervals([interval]) returns Array
• temper.chords([chord]) returns Array
• temper.scales([scale]) returns Array
• temper.temperaments([temperament]) returns Array

These all can be called with or with out an argument. When called without they will list out the available properties of their namesake. When called with an argument, they return the value of the named property.

Example

var a440 = temper.chords(440);

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Considerations

Browser support

Since the purpose temper of is to provide helpers for the web audio api, I made no effort to support legacy browsers. And while temper's main JavaScript functionality will work in any modern browser, only those that support the web audio api will be able to use playback. Sorry IE. Browser Compatibility Table

Midi Notes

Currently

Note Naming Scheme

temper.js makes use of Scientific Pitch Notation where octaves begin with C and where C4 is middle C.

Roadmap

• Precision MIDI values for non-standard tunings
• Better (interactive) Documentation
• Better support for intervals greater than an octave
• Better support for enharmonic equivalents
• Figured Bass / Chord inversion support
• Integration with Vexflow

Licence

MIT