About

Human vision perceives electromagnetic radiation between 380nm and 780nm. Sound occupies a separate physical domain - pressure waves from roughly 20Hz to 20,000Hz. No direct physical bridge exists between photon wavelength and acoustic frequency. This tool constructs one through logarithmic mapping: the HSL hue angle H (0° - 360°) drives an exponential interpolation across a three-octave piano range (130.8Hz to 1046.5Hz, C3 - C6). Saturation S modulates a low-pass filter cutoff, so desaturated greys sound muffled while vivid colors ring bright. Lightness L shapes amplitude - extremes near black or white fade toward silence, mirroring how those poles carry minimal chromatic information.

The mapping is a convention, not a law of physics. Scriabin, Newton, and Castel each proposed different color - pitch associations. This implementation uses logarithmic frequency spacing because human pitch perception is logarithmic (each octave doubles in frequency). The chord mode decomposes a color into its R, G, B channels and assigns each an independent oscillator, producing a three-note chord unique to every 24-bit color. Limitation: the audible result depends on your speakers and hearing range. Low-quality transducers may not reproduce bass frequencies below 200Hz accurately.

Formulas

The primary mapping converts HSL hue to audio frequency using logarithmic interpolation across a defined range:

f = f_min × f_maxf_min^H360

Where f_min = 130.81 Hz (C3), f_max = 1046.50 Hz (C6), and H is the hue angle in degrees (0 - 360).

Saturation controls filter brightness through a low-pass cutoff frequency:

f_cutoff = 200 + S × 8000

Where S ∈ [0, 1]. At zero saturation, the cutoff is 200 Hz (muffled). At full saturation, it reaches 8200 Hz (bright).

Lightness maps to gain with a parabolic envelope that silences extremes:

G = 1 − (2L − 1)²

Where L ∈ [0, 1]. Maximum gain occurs at L = 0.5. At L = 0 (black) or L = 1 (white), gain drops to zero.

In chord mode, each RGB channel maps independently:

f_R = 130.81 × 2^{R × 2 ÷ 255}

Same formula applies for f_G and f_B, producing three simultaneous oscillators. The ratio R ÷ 255 normalizes the 8-bit channel to [0, 1], then scales across two octaves per channel.

Reference Data

Hue Range	Color	Approx. Frequency	Musical Note	Light Wavelength
0°	Red	130.8 Hz	C3	700 nm
30°	Orange	155.6 Hz	D♯3	620 nm
60°	Yellow	185.0 Hz	F♯3	580 nm
90°	Chartreuse	220.0 Hz	A3	560 nm
120°	Green	261.6 Hz	C4	530 nm
150°	Spring Green	311.1 Hz	D♯4	510 nm
180°	Cyan	370.0 Hz	F♯4	490 nm
210°	Azure	440.0 Hz	A4	480 nm
240°	Blue	523.3 Hz	C5	470 nm
270°	Violet	622.3 Hz	D♯5	450 nm
300°	Magenta	740.0 Hz	F♯5	Non-spectral
330°	Rose	880.0 Hz	A5	Non-spectral
360°	Red (wrap)	1046.5 Hz	C6	700 nm
Waveform Reference
Sine		Pure tone, no harmonics. Clean and minimal.
Triangle		Odd harmonics only, falling at 1/n². Soft, flute-like.
Sawtooth		All harmonics, falling at 1/n. Bright, buzzy, string-like.
Square		Odd harmonics only, falling at 1/n. Hollow, clarinet-like.

Frequently Asked Questions

Human pitch perception follows a logarithmic scale. Each musical octave represents a doubling of frequency. A linear mapping would compress low pitches and stretch high pitches unnaturally. Logarithmic interpolation ensures that equal angular steps on the hue wheel produce equal musical interval steps, which sounds perceptually uniform.

The lightness-to-gain formula G = 1 − (2L − 1)² produces zero gain at both extremes. Black (L = 0) and white (L = 1) carry no chromatic information, so silence is the correct acoustic representation. Near-black and near-white colors produce very quiet tones.

Saturation controls a low-pass filter cutoff from 200 Hz to 8200 Hz. A desaturated grey color rolls off upper harmonics, producing a dull, muffled sound. A fully saturated color allows harmonics through, creating a brighter, richer timbre. The fundamental frequency (pitch) remains unchanged - only the spectral content shifts.

Not necessarily. The three RGB oscillators map independently across two octaves each. Certain color combinations produce consonant intervals (e.g., pure red at 130.8 Hz with zero G and B yields a single tone). Others produce dissonant clusters. This is by design - the chord faithfully represents the color's RGB decomposition rather than forcing musical harmony.

Magenta and rose do not correspond to single wavelengths of visible light. They are perceived when the eye receives a combination of red and blue/violet wavelengths simultaneously. The brain interpolates a hue that does not exist on the electromagnetic spectrum. The hue wheel includes them as angular positions between 300° and 360°, but no single photon wavelength produces these colors.

It provides a consistent, repeatable mapping from color to sound, which could serve as a reference in synesthesia studies or as an auditory feedback mechanism for color-blind users. However, individual synesthetic associations are highly personal and rarely match any standardized mapping. The tool approximates a systematic correspondence, not a neurological one.