The Tone Generator

How the Online Tone Generator Works

A tone generator produces a pure audio signal at a precise frequency measured in hertz (Hz). Every musical pitch corresponds to an exact frequency: concert A is 440 Hz, middle C is 261.6 Hz, and the lowest audible rumble sits around 20 Hz. Set any frequency between 1 and 20,000 Hz, choose a waveform — sine, sawtooth, square, triangle, or white noise — and the browser synthesizes it in real time using the Web Audio API. No server, no install, no data collection. All sound generation is local to your device.

The synthesizer extends the oscillator with four independent voice channels, FM (frequency modulation) synthesis for complex harmonic textures, a granular engine for pitched noise and texture work, a programmable step sequencer, and a full studio effects chain: reverb, delay, chorus, phaser, distortion, and bit crusher. MIDI controller support lets you play and automate parameters from hardware. The rack edition exposes the same engine in a modular interface suited to patch-based sound design.

Binaural beats are an auditory phenomenon produced when two slightly different frequencies are presented one to each ear via headphones. The brain perceives the difference as a rhythmic pulse — a 200 Hz tone in the left ear and 207 Hz in the right create a 7 Hz theta-wave beat, associated with relaxation and light meditation. Delta beats (0.5–4 Hz) correspond to deep sleep; theta (4–8 Hz) to meditation; alpha (8–14 Hz) to relaxed focus; beta (14–30 Hz) to active cognition. The sound bowl module generates sustained tones well-suited to this technique.

The sound bowl module includes presets tuned to the solfeggio frequencies — a scale rooted in Gregorian chant and widely used in sound healing: 396 Hz, 417 Hz, 528 Hz (the so-called miracle tone), 639 Hz, 741 Hz, and 852 Hz. Crystal and Tibetan singing bowls produce rich, slowly-decaying resonances that sit naturally in this range. Sustained bowl tones are also a foundational tool in meditation, breathwork, and therapeutic sound practice.

Cymatics is the study of visible sound — the geometric patterns that vibrating surfaces impose on matter. In the 18th century, physicist Ernst Chladni discovered that bowing a sand-covered metal plate at its resonant frequency causes the sand to migrate to nodal lines, forming symmetric figures now called Chladni figures. At higher frequencies the patterns multiply in complexity — mandalas, hexagonal lattices, and star-burst radial symmetries. Michael Faraday later documented standing-wave patterns on the surface of vibrating liquids, called Faraday waves, which show period-doubling and chaotic behavior as amplitude increases. The cymatics visualizer (in development) will render these phenomena in real time, driven by the tone generator's frequency and amplitude output.

What Is Infrasound

The human ear perceives sound between roughly 20 Hz and 20,000 Hz. Infrasound is everything below that threshold — frequencies so low they register as physical sensation rather than audible pitch. Earthquakes generate infrasound. So do ocean waves, volcanic eruptions, large weather systems, and the low-frequency calls of elephants and whales, which travel hundreds of miles through ground and water at these frequencies.

At infrasound frequencies, sound becomes structural. It interacts with large objects — rooms, buildings, the body — rather than with the small hair cells of the inner ear. A sustained tone near 18 Hz can set up standing waves in certain room dimensions, producing feelings of unease that have no obvious source. Jet engines, industrial HVAC systems, and wind turbines all generate infrasound as a byproduct, and its effects on the body at high amplitudes — disorientation, pressure, heightened anxiety — have been studied in occupational health and architectural acoustics.

The Schumann resonance at 7.83 Hz is the fundamental electromagnetic resonant frequency of the cavity between the Earth's surface and its ionosphere, excited continuously by lightning strikes around the planet. It sits squarely in the theta brainwave band (4–8 Hz), and some researchers have noted correlations between it and human neurological activity, though the mechanisms remain debated. Whether or not the biological connection holds, 7.83 Hz is a genuinely remarkable frequency: planetary, ancient, and measurable with basic equipment.

Practical uses for a low-frequency oscillator: testing speaker and subwoofer frequency response; measuring the acoustic resonant properties of a room; driving physical vibration for cymatics experiments; generating very-low-frequency binaural entrainment tones; or simply exploring the boundary between sound you hear and sound you feel. Above 20 Hz the tone becomes audible as deep sub-bass — the lowest register of a pipe organ, a kick drum's fundamental, the subsonic pressure of a concert hall.

What Is Cymatics — And Why Infrasound Makes It Visible

Cymatics is the study of visible sound — the geometric patterns that acoustic vibration imprints on matter. Sprinkle fine sand or salt on a rigid plate and drive it with a sustained tone. The sand migrates away from the vibrating regions and settles at the nodal lines — the places of stillness in the standing wave — forming a precise geometric figure. These are Chladni figures, named after Ernst Chladni, the German physicist who first mapped them in the 18th century by bowing metal plates with a violin bow and observing the sand patterns that emerged.

The figures are mathematically determined. Low frequencies produce simple forms: a cross, a diamond, a surface divided into quadrants. As frequency rises, complexity compounds — four-fold symmetry gives way to eight-fold, then to interlocking rings and radial lattices that resemble mandalas. The geometry is not an aesthetic accident; it is the direct spatial signature of the standing wave. Michael Faraday documented the same phenomenon on vibrating liquid surfaces — Faraday waves — which exhibit period-doubling and transitions to chaos as amplitude increases. Every frequency has a corresponding form.

Here is the direct connection to infrasound: Chladni experiments work best at low frequencies. Below 100 Hz, the nodal patterns are large enough to observe with ordinary sand or salt on a plate of modest size. At infrasound frequencies — 7 Hz, 10 Hz, 14 Hz — the patterns are the most fundamental possible: the simplest geometric divisions a standing wave can impose on a surface. A plate driven at 7.83 Hz, the Schumann resonance, produces a specific standing wave geometry. Shift to 10 Hz and the form reorganizes. Move up through the alpha–beta boundary at 14 Hz and a more complex figure emerges. Every preset on the infrasound oscillator corresponds to a distinct cymatics pattern.

The relationship runs deeper than experiment. Both infrasound and cymatics point to the same underlying phenomenon: vibration as a structuring force. Sound at sub-audible frequencies doesn't disappear — it becomes pattern. The frequencies you cannot hear become forms you can see. This is why cymatics practitioners, acoustic researchers, and sound healers have long worked with infrasound-range tones: not because they are heard, but because their effects on physical matter — and possibly on biological tissue — are more direct and measurable than audible frequencies. The cymatics visualizer in development on this site will render these standing wave patterns in real time, driven by the oscillator frequency and amplitude you set.