Pure tone generator.

The pure mode is part of the same free web generator that produces our binaural beats and isochronic pulses. It is not a bank of pre-recorded files: the tone is synthesised in real time by the Web Audio API on your own device, so you can dial in any frequency between 60 and 1000 Hz — including decimal values like 136.1 — and the pitch changes instantly while you listen. Nothing is uploaded, nothing is recorded, and there is no account to create.

Because a pure tone is one steady sine wave with no beat and no stereo trickery, it is the most forgiving mode in the tool: it needs no headphones. A laptop speaker, a phone on the desk, or a single earbud all reproduce it faithfully. If the bare tone feels too clinical, you can layer white, pink, or brown noise under it from the same screen, and you can switch to binaural or isochronic mode mid-session without stopping the audio.

Free sessions run up to 20 minutes. The web tool generates sine waves only; the mobile app's Frequency Lab adds square, triangle, and sawtooth waveforms, an oscilloscope view, and a multi-stage sweep designer — but for hearing what a specific frequency in hertz sounds like, the browser version is the complete tool, not a demo.

A pure tone is the simplest sound that can exist: air pressure rising and falling in a perfect sine wave at a single frequency. Hertz (Hz) just counts those cycles per second — a 440 Hz tone vibrates 440 times a second, and doubling the number raises the pitch by exactly one octave. Almost nothing in nature sounds like this. A piano string playing the same A carries a whole stack of harmonics above the fundamental; a sine tone is that fundamental with the stack stripped away, which is why pure tones sound so smooth, almost placeless.

That simplicity is what makes a pure tone generator useful as an exploration tool. When a tradition or a video makes a claim about "the frequency 528 Hz", a sine tone is the only way to hear exactly that frequency and nothing else — no instrument timbre, no production, no mix. You can compare 432 Hz against 440 Hz back to back, find the frequencies that resonate in your room, or simply learn to connect numbers to pitches by ear.

It is also what separates pure mode from the tool's other two modes. A binaural beat plays a slightly different tone in each ear and lets your brainstem construct a rhythmic illusion from the difference — that one demands stereo headphones. An isochronic tone pulses a single tone's volume at a target rate. Pure mode is the baseline both are built on: the carrier alone, steady, with no beat at all.

These are the frequencies people most often come to a tone generator to hear. Each "Play" link opens the generator in pure mode with the frequency already set — one tap and it is sounding. Be clear about what the third column is: for the solfeggio tones and 432 Hz, the descriptions are cultural tradition, not science — no research has tested whether these specific tones do what the tradition says. The linked pages separate the claims from the evidence in detail.

Two of the rows deserve a note. 440 Hz is on the list not for any special property but because it is the reference everything else is measured against — it is simply the pitch orchestras tune to. And the Schumann resonance is the honest odd one out: 7.83 Hz is a genuine physical phenomenon, but it sits far below the roughly 20 Hz floor of human hearing and below this generator's 60 Hz minimum, so any product selling you a "7.83 Hz tone" is selling something else. The Schumann resonance page explains what it actually is and how a binaural beat can represent it.

It is not a hearing test. Real audiometry uses calibrated equipment producing known sound-pressure levels in a controlled room, administered by someone trained to interpret the results. A browser tone passes through your volume setting, your device's amplifier, your speakers' frequency response, and any system EQ before it reaches you — none of it calibrated, all of it different on every device. Whether you can or cannot hear a tone here tells you nothing reliable about your hearing. If you have ringing, muffling, or any concern about your ears, see an audiologist; this page is for listening and exploring, and nothing more.

It is not a therapy device. Playing a 528 Hz or 432 Hz sine tone is a listening experience — sometimes a genuinely pleasant, meditative one — but no controlled research has tested the healing claims attached to specific frequencies, and we will not pretend otherwise. If a tone helps you settle into meditation or focus, that is a fine reason to use it; it is just not a medical one.

One practical caution: keep the volume moderate. A continuous tone at high volume is harder on your ears than it feels, because there is no natural pause in the signal. Set it just loud enough to hear comfortably — nothing about a pure tone works better louder.