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Test speakers, find a rattle in your car, check the range of your hearing or tune to a reference pitch. This generator plays a continuous tone at any frequency from 20 Hz to 20 kHz, in four classic waveforms, right in the browser.
Processing locally on your device
Overview
The tone comes from a Web Audio OscillatorNode, which synthesizes the waveform mathematically in real time rather than playing a recording, so any frequency in range is exact. A logarithmic slider covers 20 Hz to 20 kHz, which matters because hearing works in octaves: 20–40 Hz is one octave and so is 10–20 kHz, so a log scale gives each octave equal room on the slider. For precise values, type a number, nudge it with the ±1 Hz buttons, or jump an octave with ÷2 and ×2. Changes to frequency and volume are smoothed while the tone plays, so you can sweep without clicks.
The four waveforms sound very different because of their harmonics. A sine wave is a pure single frequency, ideal for testing and hearing checks. A square wave contains only odd harmonics at 1/n strength, giving a hollow, buzzy tone. A sawtooth contains every harmonic at 1/n, sounding bright and brassy. A triangle also has only odd harmonics, but they fall off faster at 1/n², so it is softer, somewhere between sine and square.
Presets jump straight to useful frequencies: 60 Hz for subwoofer and hum checks, 100 Hz and 250 Hz for bass and low-mid testing, 440 Hz as the A4 tuning reference, 1 kHz as the standard test tone and 10 kHz for treble and hearing checks. The display also shows the nearest musical note and how many cents above or below it you are, based on A4 = 440 Hz. The generator plays live only; it does not export audio files.
| Note | Frequency (Hz) | Note | Frequency (Hz) |
|---|---|---|---|
| C4 (middle C) | 261.63 | G4 | 392.00 |
| D4 | 293.66 | A4 | 440.00 |
| E4 | 329.63 | B4 | 493.88 |
| F4 | 349.23 | C5 | 523.25 |
Choose a waveform: sine, square, sawtooth or triangle.
Set the volume low before you start.
Pick a preset, drag the logarithmic slider or type an exact frequency.
Press play, then fine-tune with ±1 Hz or jump octaves with ÷2 and ×2.
Read the nearest note and cents offset if you are tuning.
Use cases
Play low sine tones around 30–80 Hz to check a subwoofer’s response, or sweep slowly to find frequencies that make panels or shelves rattle.
Raise a quiet sine tone gradually toward 15–20 kHz to see where it fades for you; the upper limit typically declines with age.
Play 440 Hz or any note frequency as a steady drone to tune an instrument or practice singing in pitch.
Show how waveforms and harmonics sound different, or how pitch doubles with each octave using the ×2 button.
Pro tips
Answers to common questions about the tone generator.
Many adults cannot hear above about 15–17 kHz, and the upper limit tends to fall with age. Some speakers and headphones also roll off high frequencies. Keep the volume low when testing; turning it up does not make inaudible tones safe.
It is logarithmic, so each octave takes the same slider distance. The range from 10 kHz to 20 kHz covers the same space as 20 Hz to 40 Hz, which matches how we perceive pitch.
It shows how far the current frequency is from the nearest note in equal temperament, based on A4 = 440 Hz. 100 cents equal one semitone, so +50 cents is halfway to the next note.
No, the generator plays tones live in the browser and does not export audio. You can record its output with another app if you need a file.
Sine for testing, hearing checks and tuning references. Square, sawtooth and triangle are useful for hearing harmonics, retro synth sounds or electronics demonstrations.
No. ToolEnhancer processes files on your own device inside the browser. They are never sent to, stored on or seen by our servers.
Yes. The tone generator is free to use with no sign-up, no watermarks and no daily limits.