Online Tone Generator

Play any frequency instantly and compare pitches by ear

This online tone generator makes a sound at any frequency from 20 Hz to 20,000 Hz right in your browser. Type a number or drag the ruler to set the frequency, pick a sine, square, triangle or sawtooth wave, and press Play. If you change the frequency or waveform while the sound is playing, it changes without a break, so you can move back and forth between two pitches and compare them by ear.

There are three modes. Single tone plays one sound in both ears or in one ear. L/R tones plays a different frequency in the left and right ear and shows the difference between the two. Sweep glides from a start frequency to an end frequency over a set time, and if you press 'Hold this frequency' at any moment, it stops at that pitch and keeps playing. You can save the frequencies you find, tap them to hear them again, and copy the list for your notes or a medical appointment. Every sound is synthesized on the spot, with no microphone and no audio files.

When you need a tone generator

Many jobs call for one sound at a known pitch. Music and video contain many frequencies at once, so it is hard to tell which pitch causes a problem. A sound with a single frequency (a pure tone) narrows the cause down to that one frequency.

• A speaker, car or room rattles: when a part resonates with a low sound, you hear a buzz. Raising the frequency slowly with a sweep shows where the rattle starts, and holding that pitch lets you touch the parts by hand to find the one that is rattling.
• You need to describe the pitch of your tinnitus: it is hard to tell someone how high a ringing sound is. If you find a similar tone and write down its frequency, it can help you describe the symptom at an appointment.
• You are tuning an instrument or setting a reference pitch: without a tuner you can still tune by ear against a reference such as A4. If your ensemble uses a different reference such as 442 Hz, change the reference and every note is recalculated.
• You wonder how high your ears and your device can hear: sweep upward and see where the sound disappears. That point depends not only on your ears but also on whether your earphones or speakers can reproduce that pitch.
• You are checking audio equipment or demonstrating sound in class: play sound separately in the left and right channels, and show how the feel of a sound changes with the waveform, along with the waveform display.

How to use it

1. Start with the device volume below the midpoint. The volume field of this tool starts at −20 dB. If the sound is too quiet, raise the tool's volume first, and raise the device volume only if it is still too quiet.
2. Choose a mode. Pick 'Single tone' to keep listening to one pitch, 'L/R tones' for different pitches in each ear, and 'Sweep' to scan across pitches. If you know your task, press one of the 'Quick starts' buttons. The frequency, waveform and volume for that task are filled in at once.
3. Set the frequency. Type a number in the field, press and drag the ruler left or right, or use the − and + buttons. The size of each − or + step is chosen in 'Step size': 1 Hz, 10 Hz, semitone or octave. The ↑ and ↓ keys in the frequency field move by the same step.
4. Press Play and adjust as you listen. Changes made while the sound is playing apply immediately. When you find the frequency you want, press 'Save this frequency'.
5. Compare or copy the saved list. Tap a frequency in the saved list to switch the sound to it. You can alternate between two candidates to hear which one is closer, and 'Copy' copies the whole list as text.

The three modes

In the waveform display, the top line is the left channel and the bottom line is the right channel. If sound goes to one side only, the other side becomes a flat line, so you can see at a glance which side is playing. The width always shows 2.5 cycles, and the bottom right corner gives that width in milliseconds. The ruler shows the current frequency, the position of the harmonics (when the wave is not a sine), the frequencies you saved, and the piano range, the voice range and the most sensitive band of hearing. The voice band combines the usual fundamental frequency of adult speech (about 90–155 Hz for men and 165–255 Hz for women).

How to find a speaker or car rattle

A rattle usually happens at specific frequencies only. A panel in a speaker cabinet, a loose screw, or a wire or plastic part inside a door each has a pitch at which it resonates easily, and it buzzes only while a sound at that pitch passes through. With music you cannot tell when it will rattle, but if you change the frequency slowly in one direction, the point where the rattle appears shows up.

1. Under 'Quick starts', press Find speaker rattle. This sets up a sine sweep that rises on a log scale from 20 Hz to 500 Hz over 30 seconds.
2. Play it at the volume you normally listen at. A rattle is easier to hear when it is louder, but starting loud puts strain on your speakers and your ears.
3. The moment you hear a rattle or buzz, press Hold this frequency. The sound stops at that frequency and keeps playing, and the mode changes to Single tone.
4. Set the step size to 1 Hz and move up and down with − and + to find the frequency with the strongest rattle, then save it. With that sound playing, lightly press the parts you suspect. The place where the rattle stops is the cause.
5. If several places rattle, press Save this frequency during the sweep to mark them one after another without stopping. Saved frequencies appear on the ruler as small triangles.

You can change the sweep range in the start and end fields. To look at very low sounds, such as a subwoofer, narrow it to 20 to 120 Hz. To find parts that rattle at somewhat higher sounds, such as a door or dashboard, narrow it to 100 to 1,000 Hz and make the time longer. The narrower the range and the longer the time, the less likely you are to pass over the rattle.

How to match a tinnitus frequency

In tinnitus research and care, 'pitch matching' means finding the tone closest to the pitch of the tinnitus a person hears. A 2019 comparison study by Neff and colleagues in Trends in Hearing covers two approaches: a method that plays two sounds and asks which is closer to the tinnitus (2AFC), and an adjustment method that sweeps the whole range quickly and then turns a control slowly to fine-tune. The study also checked separately whether a matched pitch might be confused with the octave above or below (octave confusion), and it explains that, in refining the two-sound method, a suitable step size settled at about one semitone (1/12 of an octave). You can follow the same order with this tool.

1. In a quiet place, press Match tinnitus pitch under 'Quick starts'. This sets up a 500 Hz sine wave at a low −30 dB. Set the volume about equal to your tinnitus or slightly below it.
2. Start with the output on both sides. If you hear the tinnitus in one ear only, switch between the left and right output and choose the side that is easier to compare.
3. Drag the ruler to scan widely and find the region that sounds like your tinnitus. Then set the step size to 'Semitone' and press − and + to pick the closest spot.
4. Switch the step size to 10 Hz and then 1 Hz to narrow it down. At high frequencies, a difference of a few Hz may be hard to tell apart, so if you cannot hear a difference, you can stop there.
5. Switch the step size to 'Octave' and try + (double) and − (half). If the octave above or below is closer, move to it.
6. If you have two or more candidates, save each one and alternate between them to choose which is closer. This is similar to the two-sound method (2AFC). Your answer can change even within the same day, so repeat it two or three times and see whether you get similar values.

In the Neff study, the average tinnitus pitch that participants matched with the adjustment method was 4,697 Hz, and the average matched with the two-sound method and other evaluation methods was higher. This is only the average for the participants in that study. It does not mean your tinnitus should fall in this range.

See a clinician first. The US National Institute on Deafness and Other Communication Disorders (NIDCD) advises that if you have tinnitus, you should first see a primary care provider to check for a blockage from earwax or a middle-ear infection. An audiologist can assess hearing and tinnitus, and if the tinnitus pulses like a heartbeat, imaging tests may be done. Most people with tinnitus also have some degree of hearing loss. A frequency found with this tool is a reference value to help you explain things at an appointment, and it does not replace diagnosis or treatment. If you want to use sound for managing tinnitus, decide the method together with a clinician.

Reference pitch and note names

The most widely used reference pitch today is the A above middle C, A4 = 440 Hz. The International Organization for Standardization (ISO) adopted this value as a technical standard in 1955 and confirmed it again in 1975 as ISO 16. In real performance the reference varies a little. In 1964, 19 of 31 major American orchestras tuned to 440 Hz and the rest to 441 or 442 Hz. In a 1987 New York Times survey, most symphony and opera orchestras were between 440 and 444 Hz, and the Berlin Philharmonic uses 443 Hz. Ensembles that specialize in Baroque music often use A = 415 Hz.

In 12-tone equal temperament, each semitone up multiplies the frequency by the twelfth root of 2 (about 1.0595), and going up 12 semitones (one octave) exactly doubles it. So once you set the A4 reference, the frequency of every note is determined.

Note frequency = A4 reference × 2^{(semitones from A4 ÷ 12)}
Cents = 1,200 × log₂(frequency ÷ frequency of the nearest note)

The note name on screen shows the note nearest to the current frequency and how many cents away you are from it. One cent is one hundredth of a semitone. The table below gives the values for A4 = 440 Hz.

If you change the A4 reference, the other notes move by the same ratio. Taking middle C (C4) as an example:

When you tune by ear, a triangle or sawtooth wave can be easier to hear than a sine wave. A sine wave has no harmonics, so low notes in particular are hard to hear on a small speaker. When the reference and your instrument are almost the same pitch, you hear a slow wavering called beating, and the right pitch is where this wavering slows down and disappears.

How the waveforms sound different

A sine wave is the simplest sound, with just one frequency. The other waveforms mix in harmonics, which are whole-number multiples of the fundamental frequency, so even at the same pitch they feel different. Square and triangle waves have odd harmonics only (3rd, 5th, 7th and so on), while a sawtooth wave has both even and odd harmonics. They also differ in how quickly the harmonics get smaller.

The energy of a sound differs by waveform, so with the same peak height a square wave has the highest average level (RMS) and a sawtooth the lowest. So that the loudness does not jump when you change the waveform, this tool corrects the four waveforms so that their average level (RMS) matches the sine wave when the volume field is the same. The correction values were calculated from 1 kHz waveforms. A browser does not produce harmonics above half the playback sample rate (usually 22 to 24 kHz), so at very high frequencies the differences between waveforms shrink. The short vertical lines on the ruler show the harmonic positions of the current note: odd multiples only for square and triangle waves, and every multiple for a sawtooth wave.

Audible frequencies and the most sensitive band

The sounds people can hear are commonly given as 20 to 20,000 Hz. But individuals differ a lot, and it is normal for the high end to shrink gradually with age. The upper limit of the audible range generally starts to fall from around the age of eight.

Even at the same level, how well you hear a sound depends on its frequency. The international standard ISO 226:2023 lists the quietest sound (the hearing threshold) that healthy-eared 18 to 25 year olds can hear at each frequency. A smaller value means they can hear a quieter sound. A value below the 2.4 dB at 1 kHz marks a band more sensitive than 1 kHz.

That is why, at the same volume setting, a sound at 3 to 4 kHz tends to seem louder than one at 100 Hz. The 'Most sensitive' band on the ruler marks 2 to 5 kHz, where this table's hearing threshold is below 0 dB. When you sweep to high frequencies, keep the volume low, because the sound gets louder as it passes through this band.

When you use 'Check hearing limit' to find the frequency where the sound disappears, do not take the result as a hearing test. Some devices cannot reproduce very high sounds well, and even for the same person the frequency where the sound disappears changes with volume and device. If you are worried about your hearing, a pure-tone audiometry test at an ear, nose and throat clinic is the accurate way.

L/R tones and beats

When you hear two sounds with slightly different frequencies together, you hear a regular swelling and fading, called a beat. The speed of the wavering equals the difference between the two frequencies. Even when the sounds are played separately to each ear, for example 520 Hz in the left ear and 530 Hz in the right, you perceive a sound that wavers 10 times per second, which is called a binaural beat. Oster's 1973 article 'Auditory beats in the brain' in Scientific American covered this phenomenon.

In L/R tones, the large number on screen shows the difference between the two frequencies, and if the difference is 30 Hz or less, a light flashing at that rate also turns on. In the waveform display, the right line slides faster than the left line by the difference, so you can see the phases of the two sounds keep drifting apart. Because each ear has to hear its own sound, listen with earphones or headphones. Over speakers, the two sounds mix in the air and become an ordinary beat.

Many claims say that binaural beats are good for focus, sleep or mood, but the evidence is inconsistent. A 2023 systematic review in PLOS ONE examined 14 studies that met its criteria: five reported results consistent with the hypothesis that brain waves follow the beat, eight reported results that were not, and one reported mixed results. The authors concluded that results are generally inconsistent and that claims that binaural beats change psychological or physical states should be treated with caution. This tool only provides the ability to play different sounds in the two ears and does not promise any effect.

Reading a sweep: log and linear

A sweep comes in two types. Log rises so that each octave takes the same time, so low and high sounds are heard evenly. From 20 Hz to 20,000 Hz is about 10 octaves, so a 20-second sweep takes about 2 seconds per octave. Linear rises by the same number of Hz every second, so it spends most of its time on high sounds. Choose log to listen carefully to the low range, and linear to scan a narrow high range evenly.

Log sweep frequency = start × (end ÷ start)^{(elapsed time ÷ total time)}
Linear sweep frequency = start + (end − start) × elapsed time ÷ total time

The frequency number shown during a sweep is calculated for the moment the sound actually leaves the device. 'Hold this frequency' and 'Save this frequency' also use the frequency shown on screen at the instant you press them, as a whole number of Hz. Bluetooth earphones play sound a little late, so to find the exact point, hold the frequency and then listen again around it in 1 Hz steps.

Volume and ear protection

The World Health Organization (WHO) advises that a sound at 80 dB is safe to listen to for up to 40 hours a week, but at 90 dB the safe time drops to 4 hours a week.

The dB in the volume field shows how far below the digital maximum the peak of a sine wave sits. The real loudness reaching your ear (dB SPL) depends on the device volume and the earphones, so you cannot tell it from this number. Sounds above 15,000 Hz may be coming out of the device even if you cannot hear them. Turning the volume way up because you cannot hear them can strain your ears and the tweeter (high-frequency speaker), so this tool shows a notice when it plays such frequencies.

Common mistakes

• Starting with the device volume at maximum: a loud sound can come out the moment you press Play. Keep the device volume below the midpoint and set the level with the tool's volume first.
• Thinking the device is broken because you cannot hear low sounds: small phone and laptop speakers often cannot reproduce low sounds well. Check low sounds with earphones or a larger speaker. To check the left and right channels and the bass together, the speaker and earphone left-right test is a better fit.
• Matching the tinnitus pitch an octave off: a sound at exactly double or half the pitch is easy to mistake for the same one. After matching, always compare with the octave above and below using the 'Octave' step size.
• Listening to binaural beats over speakers: the two sounds mix in the air and both ears get the same sound. Listen to L/R tones with earphones or headphones.
• Forgetting Bluetooth delay: Bluetooth devices play sound late, so a frequency you press during a sweep may be saved slightly higher (for a rising sweep) than the one you actually heard. Hold it and listen around it again to check.

Limits

• Sound goes out through the output device chosen by the operating system and browser. This tool does not change the output device.
• The volume field is the size of the digital signal, and the tool neither measures nor sets the loudness reaching your ear (dB SPL). It is not a medical hearing test or a tinnitus diagnostic tool.
• Frequency is handled from 20 to 20,000 Hz, to two decimal places. The accuracy of the sound actually produced depends on the device's sample rate and speaker quality.
• Square, triangle and sawtooth waves are band-limited waveforms made by the browser, so they do not have perfectly sharp corners like the drawings. The waveform display is a picture showing the shape, not a measurement of the output signal.
• On a phone, the sound may stop when the screen turns off or you switch to another app. If there is no sound, return to this screen and press Play again.

Reference date: The source documents were checked on 2026-10-27.

Sources

• 01Wikipedia: Concert pitchISO adopted A440 in 1955 and reaffirmed it as ISO 16 in 1975; in 1964, 19 of 31 major US orchestras used 440 Hz (the rest 441 and 442 Hz); in 1987 most were at 440 to 444 Hz; Berlin Philharmonic 443 Hz; Baroque ensembles 415 Hz
• 02Wikipedia: Piano key frequenciesFrequency of the nth key f(n) = 2^(n−49)/12 × 440 Hz; A0 27.5 Hz, C4 261.63 Hz, C8 4,186.01 Hz
• 03Wikipedia: Hearing rangeThe human hearing range is commonly 20 to 20,000 Hz; a decline in high-frequency sensitivity with age is normal; the upper limit generally starts to fall from around the age of eight
• 04ISO 226:2023 equal-loudness-level contours (sample PDF)Table 1 hearing threshold Tf (ages 18 to 25): 1,000 Hz 2.4 dB, 3,150 Hz −6.0 dB, 4,000 Hz −5.4 dB, 8,000 Hz 12.6 dB, 12,500 Hz 12.3 dB
• 05NIDCD: TinnitusSee a primary care provider first; hearing and tinnitus assessment by an audiologist; imaging for pulsatile tinnitus; most people with tinnitus have some hearing loss (updated 2023-05-01)
• 06Neff et al. (2019), Tinnitus Pitch Matching With Respect to Reliability, Matching Duration, and Subjective Satisfaction, Trends in Hearing 23Two-sound choice (2AFC), adjustment method, octave confusion check, suitable step size about one semitone, adjustment-method average 4,697 Hz
• 07Wikipedia: Beat (acoustics)530 Hz in the right ear and 520 Hz in the left give 10 beats per second; Oster (1973), Scientific American
• 08Ingendoh, Posny and Heine (2023), Binaural beats to entrain the brain? A systematic review, PLOS ONEOf 14 studies, 5 consistent with the hypothesis, 8 not, 1 mixed; results generally inconsistent, so effect claims call for caution
• 09Wikipedia: Square wave · Triangle wave · Sawtooth waveSquare wave: odd harmonics (1/n); triangle wave: odd harmonics (inversely proportional to the square of the harmonic number); sawtooth wave: both even and odd harmonics (1/n)
• 10WHO: Deafness and hearing loss, safe listening80 dB is safe for up to 40 hours a week; at 90 dB the safe time drops to 4 hours a week
• 11MDN: OscillatorNodeA Web Audio sound source that produces sine, square, sawtooth and triangle waves at a set frequency
• 12Wikipedia: Voice frequencyFundamental frequency of adult speech: men 90–155 Hz, women 165–255 Hz

Frequently asked questions

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