Online tone generator

How to use the tone generator

A tone generator, also called a frequency generator, Hz generator or sound generator (in a lab, a signal or function generator), makes a sound wave at the frequency and shape you set; this one runs in the browser. Tap Play: a sine at 440 Hz starts at 30 % volume, and everything you change moves the running tone. Type a frequency in hertz (a decimal point or comma both work), drag the slider across the whole range from 20 Hz to 20,000 Hz, or step by a semitone (½) or an octave (8va). Or pick a note, its octave and a number of cents from −99 to +99: C4 is middle C, 261.63 Hz. The readout names the nearest note, how many cents the tone sits above or below it, and its MIDI number. It stops at 20 Hz and 20 kHz on purpose: below 20 Hz phone and laptop speakers play nothing and what is left is felt rather than heard as a tone; above 20 kHz adults hear nothing, and a device running at 44.1 kHz can't go past 22.05 kHz, half its sample rate.

Waveform changes the sound, not the pitch (below). Channel sends the tone to the left speaker, both, or the right. Test tones start 50 Hz, 60 Hz, 100 Hz, 440 Hz, 1 kHz or 10 kHz with one tap. Tuning, A4 = 432, 440 or 442 Hz moves every note with the A, so the note picker matches the band or orchestra you play with.

A sweep glides from one frequency to another over the seconds you set (up to ten minutes), the same time for every octave, so 20 Hz to 20 kHz (just under ten octaves) spends as long in the bass as in the treble. The tone downloads as a 4-second WAV loop (24-bit, 48 kHz, a whole number of cycles, so it repeats without a click) and the sweep as a WAV of up to 60 seconds, with 10 ms fades at both ends so it starts and ends without a click; both are made in the tab. There is no app to install: it runs in the browser on a phone or a computer. On a recent iPhone (iOS 17 and later) the tone plays even with the silent switch on; on an older one, if nothing comes out, flip the switch. The tone stops when you switch to another tab.

Test tones for speakers, subwoofers and headphones

Start quiet and work from low to high. 20 to 200 Hz is the bass: a subwoofer should play smoothly down to its rated limit, and a rattle, a buzz or a sudden drop shows where the speaker, or something in the room, gives up. To set a subwoofer's crossover, sweep slowly from 40 to 150 Hz: the bass should stay even through the hand-over (often 80 Hz); a hole or a bump there means the crossover frequency or the sub's phase needs moving. 200 Hz to 2 kHz holds voices and most instruments; 2 to 20 kHz is the treble, the tweeter's work. The one-tap tones: 50 Hz and 60 Hz are mains hum (50 in Europe, most of Asia, Africa and Australia; 60 in North America; Japan has both). A hum in a recording at one of them, or at twice that, 100 or 120 Hz, comes from the power, not the instrument. 100 Hz shows whether a small speaker plays any bass at all: most laptop speakers fade out around there, phone speakers higher still. 1 kHz is the tone studios and broadcasters line up their levels with. 10 kHz checks a tweeter. Left, both and right check that a cable, a pair of headphones or a stereo setup is wired the right way round: Left must come out of the left side only. With Both and a low sine around 80 to 100 Hz, two speakers side by side should sound like one source in the middle; if the bass goes thin and seems to come from everywhere, one speaker is wired with plus and minus swapped, and the two cancel. It plays tones, not noise: white, pink or brown noise covers every frequency at once (pink with equal energy per octave, the usual signal for setting speaker levels and room EQ), and this page doesn't make it.

Sine, square, triangle and sawtooth: what the waveform changes

All four repeat at the frequency you set, so the pitch is the same. What differs is which overtones ride on top, at whole-number multiples of that frequency. A sine is the pure tone: one frequency and nothing else, the one for tuning, level checks and hunting one frequency in a room. A triangle adds only the odd harmonics (3×, 5×, 7×…), falling with the square of their number: the third is 19 dB below the fundamental, so it sounds soft, close to a flute. A square has the same odd harmonics falling only with their number (the third 9.5 dB down): hollow and buzzy, the sound of old game consoles. A sawtooth has every harmonic, 2×, 3×, 4×…, each at 1/n of the fundamental: the brightest, and the raw material of most synth sounds. The browser builds them only from harmonics below half the sample rate, so a high square doesn't fold back into false tones. It also means that above about 7 kHz a square or triangle sounds like a sine, and above about 10 kHz a saw does too: their overtones lie above 20 kHz, beyond the ear.

Look after your ears, and your tweeters

Set the device volume low before the first Play, then turn up slowly; the slider here starts at 30 %, and the page warns from 70 % and from 8 kHz up. A steady tone has none of music's pauses, so keep tones short, and a high tone at the same setting sounds much louder than a low one (why, below). The WHO–ITU safe-listening standard (H.870, 2019, revised 2022) puts the weekly limit for adults at 80 dB(A) for 40 hours, 75 dB(A) for children, and every 3 dB more halves the time. Tweeters burn out on long, loud high tones, small speakers on loud deep ones. Stop if anything hurts or rings, and don't aim the tone at babies or pets: they can't turn it down.

Frequency, pitch and notes, in numbers

A frequency is how many times a second the air pressure swings back and forth, counted in hertz: 440 Hz is 440 swings a second. Pitch is how high that sounds to you. The ear hears ratios, not differences: doubling the frequency is one octave up, whether from 110 to 220 Hz or from 1,000 to 2,000 Hz. Western music splits the octave into twelve equal semitones, each a ratio of the twelfth root of 2, 1.0595, and the standard ISO 16 (1975) fixes A4 at 440 Hz. Every note follows from that: f = 440 × 2^((n − 69) / 12), with n the MIDI number. A cent is a hundredth of a semitone, 0.058 % of the frequency, 0.25 Hz at A4; played one after the other, practised listeners can tell tones about 3 to 5 cents apart in the middle of the range (Wier, Jesteadt and Green, 1977, a frequency step of about 0.2 to 0.3 %); untrained listeners need more.

Wavelengths are for sound at 343 m/s, in air at 20 °C. They explain why bass misbehaves indoors: at 50 Hz one wave is nearly 7 m long, the size of the room, and it bounces between the walls into standing waves, the room modes. The first one between two parallel walls sits at 343 ÷ (2 × the distance) Hz: 42.9 Hz for walls 4 m apart, 34.3 Hz for 5 m. Sweep slowly through the bass and walk around: a note that booms in one spot and nearly vanishes a metre away is a room mode, not the speaker.

Tuning an instrument by ear with a reference tone

Pick the string's note in the picker (a guitar in standard tuning: E2 82.41, A2 110.00, D3 146.83, G3 196.00, B3 246.94, E4 329.63 Hz), play it quietly, and play the string with it. Two tones close in frequency beat: the sound swells and fades as many times a second as they are apart in hertz. An A string at 111 Hz against the generator's 110 Hz wobbles once a second; turn the peg until the wobble slows and stops. A triangle or saw is often easier to match than a sine, because the string has overtones too. Beats need both tones in the same ear: one tone in each ear through headphones is what binaural-beat generators do, and this page plays one tone at a time, so it makes neither. To have the instrument read for you instead, use a tuner, which listens through the microphone.

The highest and lowest tones you can hear

20 Hz to 20 kHz is the textbook range, and it describes young ears. The top falls with age: many grown-ups hear nothing at 15 kHz, and that is normal. Below about 20 Hz a tone turns into a flutter you feel more than hear. In between, the ear is uneven: at 20 Hz a tone has to be about 75 dB stronger than at 1 kHz to be heard at all, and the ear is most sensitive around 3 to 4 kHz, where the ear canal resonates (the equal-loudness contours, ISO 226:2023). When a tone fades out, the speaker is often the limit before your ears are: a phone speaker plays little below a few hundred hertz, a laptop little below 100 to 150 Hz, and some Bluetooth links cut the very top. Use wired headphones for the extremes. To find your own top: a quiet sine at 8 kHz, then drag the slider up until the tone is gone and come back down until it returns; that frequency is where your ears or your headphones stop, whichever comes first. Do the same from 100 Hz downwards for the bottom. Keep the volume where it was: turning up to chase a vanishing high tone is how tweeters and ears get hurt. This page asks nothing and scores nothing; it is a tone, not audiology.

Tinnitus frequency matching

A tinnitus tone generator is the same tool used to find the pitch of the ringing. Start low with a sine, raise the frequency slowly with the slider until the tone sounds like the ring, then check an octave up and an octave down with the 8va buttons: people often match the right note in the wrong octave. Playing a soft sound at or near that pitch so the ringing stands out less is called masking; people do it for a while, at a low level. Many tinnitus sounds are a hiss rather than one tone, and a single frequency won't match those. It treats nothing: a Cochrane review of sound therapy for tinnitus (Sereda and colleagues, 2018, Cochrane Database of Systematic Reviews, CD013094) found no evidence that sound therapy beats a waiting list, placebo or education. Tinnitus that is new, sits in one ear or beats with your pulse is for a doctor first.

For producers

Pick a note and its cents to hear where an 808 or a sub should sit, and drop the WAV loop under the track as a reference while you tune. The MIDI number is the one your DAW sends: A4 = 69, middle C = 60, which some DAWs label C3 and FL Studio C5. The WAV loop always peaks at −6 dBFS, whatever the volume slider says. The usual line-up tone is a 1 kHz sine; for one at broadcast level, lower the clip by 12 dB in your DAW (EBU R 68: −18 dBFS) or by 14 dB (SMPTE RP 155: −20 dBFS). To find the note of a sample, use the pitch detector; to tune an 808, the 808 tuner; for every note's frequency, the note frequency chart.

432 Hz, 528 Hz and other famous frequencies

The 432 Hz button under Tuning retunes every note so A4 = 432 Hz: the same melody 31.8 cents lower, a third of a semitone, and an A at 432 against one at 440 beats eight times a second. Where 432 comes from, and what is and isn't true about it, is on the 432 Hz tuner. 528 Hz and the other "solfeggio frequencies" (396, 417, 528, 639, 741 and 852 Hz) spread from a 1999 book by Leonard Horowitz and Joseph Puleo, Healing Codes for the Biological Apocalypse; they have nothing to do with the ut-re-mi syllables Guido of Arezzo used in the 11th century, which named steps of a scale, not fixed pitches, and the hertz itself was only named in 1930 (IEC). Type any of them in and they play like any other number: 528 Hz is C5 plus 15.6 cents at A = 440. What they are said to do to the body is beyond what a tone generator measures, and this page makes no claim either way.

How exact is the tone?

The page asks the browser's audio engine (the Web Audio API) for an oscillator at your frequency; it computes the wave usually 44,100 or 48,000 times a second, depending on the device, and the device's converter and speaker turn those numbers into air pressure. It computes in floating point, so it plays the number you typed, far finer than a cent. What varies is the device's clock, typically within about 0.01 % (under a fifth of a cent), and what the speaker can reproduce. The WAV loop moves the frequency by at most 0.005 cents so the cycles fit the samples exactly; the line under the button gives the frequency it saved.

Other things called a tone generator

Electricians mean something else by a tone generator and probe, or a wire tracer: a small box that puts a tone on a cable at one end, and a probe that makes it audible at the other, to find which wire in a bundle is which. That is hardware; this page makes sound in the air, not a signal on a wire. A DTMF or touch-tone generator plays a phone keypad's tones, two at once: a row tone (697, 770, 852 or 941 Hz) and a column tone (1209, 1336 or 1477 Hz, and 1633 Hz for the rare A to D keys), set by ITU-T Q.23. Here you can play each half, one at a time, not the pair. A ring tone generator, in the sense people search for it, makes ringtones from songs; this one gives you a plain tone as a WAV file, which phones that accept WAV can use as a ringtone or alarm sound.

Then make something of it

"Play it in a track" puts the note you were on into Brumm as a melody, inside a club track with a beat and a bass. No account, no upload: the note travels inside the link itself. Hum a whole line there, and it becomes an instrument.

No microphone here: the tone is made in your browser and nothing is sent anywhere. How the site counts visits.