Online tone generator any frequency from 1 to 22,000 Hz

How to use the online tone generator

The generator above plays any frequency from 1 to 22,000 Hz. Drag the slider, which is logarithmic from 20 to 20,000 Hz so every octave gets the same space, or type an exact number. Choose a sine, square, triangle or sawtooth wave, send it to the left channel, the right channel or both, and play it continuously, as beeps or as short bursts. Under the frequency you see the nearest musical note and how many cents the tone is above or below it. The sweep mode glides from one frequency to another in 5 to 120 seconds, logarithmically or linearly, and shows the frequency live as it moves.

Three habits give a clean result. First, set your device volume low before you press Play and raise it slowly; a pure tone can be unpleasant long before it seems loud. Second, use headphones or a proper speaker for anything below about 60 Hz or above about 15 kHz, because phone and laptop speakers reproduce deep bass weakly or not at all and many also lose the highest treble. Third, start with a sine wave: it is a single frequency, so what you hear is exactly the number on the screen.

If a tone seems silent, check in this order: volume, output device, the channel setting, then the speaker itself. Only after that does it make sense to think about your ears.

What is the frequency of sound? Hz, pitch and wavelength

The frequency of a sound is how many times per second the air vibrates, measured in hertz: 1 Hz is one vibration a second, and 1 kHz is 1,000 Hz. Pitch is how high or low we hear a tone, and it rises with frequency. Each doubling of the frequency is one octave, so 220 Hz, 440 Hz and 880 Hz are all the note A, one octave apart.

Two other numbers come straight from the frequency. The period, the time one vibration takes, is 1 divided by the frequency: 100 Hz lasts 10 ms per cycle, 1 kHz lasts 1 ms. The wavelength in air is the speed of sound divided by the frequency. At 20 °C sound travels at about 343 m/s (about 331 m/s at 0 °C), which gives these values:

The spread is striking: a 20 Hz wave is about as long as four cars parked nose to tail, while a 20 kHz wave would fit on a fingernail. That thousandfold difference is why a single small speaker struggles to play both ends of the range well.

Sine, square, triangle and sawtooth waves: what is the difference?

A sine wave contains one frequency and nothing else, which is why it is called a pure tone. The other three waveforms repeat at the same rate, so you hear the same pitch, but each adds overtones (harmonics) at whole-number multiples of the base frequency. Which harmonics are present and how fast they fade gives each wave its colour.

A practical example: a 1,000 Hz square wave also sends energy at 3,000, 5,000, 7,000 Hz and up, so it sounds buzzier and louder than a 1,000 Hz sine at the same volume setting. For measuring, matching or testing hearing, use the sine. For hearing how a speaker copes with complex sound, or for a science lesson on harmonics, compare the same frequency across all four waves.

The square wave generator is also the easiest way to hear that harmonics move with the base note. Set 200 Hz and listen, then 400 Hz: the whole buzzy texture moves up an octave together, because every harmonic doubled too.

Why do some frequencies sound louder than others?

Your ear is not equally sensitive to all pitches, so tones at the same level do not sound equally loud. The international standard ISO 226:2023, "Acoustics: Normal equal-loudness-level contours", maps which combinations of sound pressure and frequency sound equally loud. It was measured with otologically normal listeners aged 18 to 25, for pure tones from 20 Hz to 12,500 Hz. Its message is simple: very low and very high tones need much more sound pressure to sound as loud as mid tones.

Hearing is sharpest between about 2,000 and 5,000 Hz. Part of the reason is the ear canal itself. It is a tube about 25 mm long, closed at one end by the eardrum, and such a tube resonates at a quarter of a wavelength: 343 m/s divided by 4 × 0.025 m is about 3.4 kHz. Studies of the ear describe this canal resonance in the 2 to 4 kHz region and link it to a 3 kHz peak in sounds the ear itself emits.

This matters when you use the generator. If you sweep from 50 Hz to 15 kHz at a fixed volume, the tone will seem to swell through the middle and fade at both ends even when the speaker is perfect. Do not judge a speaker's bass or treble by loudness alone; listen for rattles, distortion and the point where the tone disappears.

What frequencies can humans hear? High frequency tones and age

The human hearing range is commonly given as 20 Hz to 20,000 Hz, with considerable variation between people, especially at high frequencies, and a gradual loss of high frequencies with age is considered normal. Sound below about 20 Hz is called infrasound and sound above 20 kHz ultrasound.

The top of the range fades sooner than most people expect. In a 2021 study of 162 healthy adults aged 21 to 70 with normal standard hearing tests, everyone under 30 heard 16 kHz and 52.2 % heard 20 kHz. No one aged 51–60 heard 20 kHz, and no one aged 61–70 heard even 18 kHz. A Norwegian study found that young adults aged 18–24 already heard the highest tones less well than children aged 8–14.

The same fact is behind the "Mosquito", an anti-loitering device that plays a pulsing 16–18.5 kHz tone most people under 20 can hear and most people over 25 cannot. In 2010 the Parliamentary Assembly of the Council of Europe recommended banning its use in public places.

When you use the generator as a high frequency tone generator, remember that there is also a ceiling on the device side. Digital audio can only carry frequencies below half the sampling rate: 22.05 kHz at 44.1 kHz and 24 kHz at 48 kHz. That is why the generator stops at 22,000 Hz, and why a tone at 18 kHz that you cannot hear may simply not be coming out of the speaker. The page about the hearing frequency test goes through this step by step; it is a rough self-check, not a medical hearing test.

Low frequency sound: what 20 Hz and 100 Hz really sound like

Low frequency sound sits at the bottom of the hearing range, roughly from 20 Hz to a few hundred hertz. A 20 Hz tone is the textbook lower limit: below it begins infrasound, and near it, at higher intensities, the vibration is partly felt in the body rather than heard as a clear pitch. A 100 Hz tone is a deep hum with a wavelength of about 3.4 m.

Most disappointments with bass tones come from the speaker. Microspeakers in phones and laptops have very little room behind the cone, and size limits are a known challenge for their sound. In practice, deep bass tones may be inaudible on them. If 30–60 Hz is silent, try headphones or a proper speaker before concluding anything.

For home cinema, 80 Hz is a useful landmark: THX requires an 80 Hz crossover point in the setup menu of certified receivers, and it is a common starting point for handing bass to a subwoofer. It is not the ideal value for every system. The page about the speaker and headphone test has a bass sweep from 20 to 200 Hz and single tones for checking a subwoofer.

440 Hz (A440): the standard tuning tone

440 Hz is the international standard frequency for the note A above middle C. ISO 16:1975 specifies 440 Hz for the A in the treble stave, to an accuracy of 0.5 Hz. The standard has a long history: France fixed A at 435 Hz on 16 February 1859, delegates of five countries agreed on 440 Hz in London in May 1939, ISO adopted it in 1955 and confirmed it as ISO 16 in 1975.

From A440 every other note follows. In equal temperament the octave is split into 12 equal semitones, each a frequency ratio of 2^(1/12), about 1.05946, so each key is about 6 % higher than the one below. A piano runs from A0 at 27.5 Hz to C8 at about 4,186.01 Hz, and middle C is about 261.63 Hz.

The generator shows the nearest note in cents. A cent is a hundredth of an equal-tempered semitone, 1,200 to the octave, and the interval between two frequencies in cents is 1,200 × log2(f2 / f1). Between 432 Hz and 440 Hz there are 31.77 cents, about a third of a semitone; the debate about the two tunings is covered on the page about 432 Hz vs 440 Hz. For hearing how small a cent is: above 1,000 Hz the just-noticeable pitch difference is roughly 0.6 %, about 10 cents, while below 500 Hz it is roughly 3 Hz for sine tones. These figures depend on the method and are approximate.

To tune with the generator, play 440 Hz on a sine wave and adjust your instrument's A until the slow wobble between the two sounds disappears. The full note-by-note table is on the note frequency chart page, and the tuning fork page plays classic forks such as 440, 432 and 512 Hz.

Frequency sweep: how to test speakers and headphones with tones

A frequency sweep is a tone that glides steadily from one frequency to another. Played slowly from low to high, it reveals rattles, buzzing, dead zones and the point where a speaker stops producing sound. The room also shapes what you hear, so move around or try headphones if one note booms and the next vanishes.

The generator offers two kinds of sweep. A logarithmic sweep spends equal time on every octave, which matches how we hear pitch: 20 to 40 Hz takes as long as 10 to 20 kHz. From 20 Hz to 20 kHz is about ten octaves, so a 60-second log sweep spends about six seconds per octave. A linear sweep moves the same number of hertz every second, so it races through the bass and lingers in the treble; it is useful when you care about a narrow high band.

Two more checks need nothing but a tone and two ears. Send the tone to the left channel only: it must come from the left side only, and if it comes from the right, the channels are swapped in the wiring or settings. And if bass sounds thin and the stereo image seems to come from nowhere, one speaker's wires may be reversed, so the two cones move in opposite directions and cancel each other at low frequencies, where the wavelength is long compared with the speaker spacing.

What can you use a tone generator for?

An online tone generator, frequency generator or hz generator does one thing: it plays a chosen frequency through your speakers. That simple job covers a surprising range of uses.

• Speakers and headphones: left and right channels, rattles in a sweep, where the bass and treble end.
• Hearing curiosity: finding the highest tone you can hear on good headphones, and seeing how it compares with the age data above.
• Tuning: a steady 440 Hz reference, or any other pitch, with the nearest note and its cents offset shown.
• Science lessons: hearing that doubling the frequency gives an octave, comparing sine and square waves to hear harmonics, and working out wavelengths from the speed of sound.
• Sound design and audio work: test tones for checking a signal chain, levels and channel routing.
• Tinnitus matching: some people try to find the approximate pitch of their tinnitus with a generator so they can describe it. This page makes no claim that any tone treats tinnitus.

If anything in these checks worries you about your hearing, for example difficulty hearing high-pitched sounds such as birds, doorbells, phones or alarm clocks, or tinnitus that does not go away, those are warning signs the World Health Organization lists for getting your hearing checked properly. WHO also offers a free app, hearWHO.

How loud is safe? Volume rules for test tones

The World Health Organization's safe-listening limit for adults is 80 dB for up to 40 hours a week, and the WHO–ITU standard for listening devices sets 75 dB for 40 hours a week for children. Because the decibel is logarithmic, the safe time shrinks fast as level rises:

For scale, WHO gives these everyday levels: a soft whisper is about 30 dB, normal conversation 60 dB, heavy traffic heard inside a car 85 dB, a hair dryer 100 dB and a siren nearby 120 dB.

WHO advises keeping device volume at no more than 60 % of maximum and warns that even a single exposure to extremely loud sound can damage the inner ear. Noise-induced hearing loss often begins with trouble hearing some high-pitched sounds, such as bells or birdsong.

Test tones add some risks of their own. If you cannot hear a high tone, do not turn it up to maximum: children, pets and the people around you may be getting far more sound than you think, and small speakers and tweeters are not built for long, loud, pure high tones. Start quiet, raise the volume slowly, keep sessions short, and stop if a tone feels uncomfortable.