Tone generator

How to use the tone generator

1. Turn your device volume down first, and keep the volume slider on this page low. A steady tone sounds louder than music at the same setting.
2. Pick a frequency: drag the slider (it is logarithmic, so the low and high ends are equally easy to reach), type a value such as 440, 1.5k or 2 kHz in the box, or use a preset.
3. Fine-tune with −1 / +1 and −10 / +10 Hz, or jump an octave with ÷2 / ×2. Changes apply while the tone is playing.
4. Choose a waveform and a channel (left, both or right), then press Play tone. Press it again, or Stop all sound, to stop. Switching to another tab stops the sound too.

Waveforms: what each one sounds like

• Sine: a single pure frequency with no harmonics. Use it to check one frequency on its own, for example whether a speaker can reproduce 40 Hz.
• Square: hollow and buzzy, with strong odd harmonics. It contains much more energy above the fundamental, so it sounds louder: lower the volume before switching.
• Sawtooth: bright and harsh, with all harmonics. Useful as a reference for synthesis or to hear how a speaker handles a rich signal.
• Triangle: softer than square, with weak odd harmonics. A gentle alternative to sine that is still easy to hear.

Square, sawtooth and triangle waves are built by the browser's oscillator, which limits harmonics to avoid aliasing; the exact shape can differ slightly between browsers.

Sweeps

A sweep moves smoothly from one frequency to another over the duration you choose (1 to 120 seconds). It glides exponentially, so each octave takes the same time, which matches how we hear pitch. Common uses:

• 20 Hz → 200 Hz to hear where a small speaker or laptop stops producing bass, and to find rattles in a desk, case or car door panel.
• 20 Hz → 20 kHz to hear the whole range your speakers and ears cover. Most adults stop hearing somewhere well below 20 kHz; that is normal and this page is not a hearing test.
• A narrow sweep around a problem frequency to find exactly where a buzz starts.

For channel and phase checks with a ready-made sequence, use the speaker test or the headphone test.

Common uses

• Reference pitch: 440 Hz is concert A, used to tune instruments.
• Speaker and subwoofer checks: play a low sine (for example 30–60 Hz) to see whether a subwoofer responds, or step through frequencies to find a rattle.
• Wiring checks: send a tone to the left or right channel only to confirm cables and speakers are not swapped.
• Teaching and experiments: show how pitch relates to frequency, compare waveforms, or demonstrate beats by playing two devices a few hertz apart.
• Audio gear: a steady 1 kHz tone is a common level reference; this page does not calibrate levels, but it gives a clean, repeatable signal.

Limits and safety

• Protect your hearing and your speakers. High frequencies and square waves can be uncomfortable at volumes that seem low. Very low frequencies at high volume can push small speakers past their limits. Start low and raise slowly.
• The page can only play what your device can reproduce. Phone and laptop speakers produce little or nothing below about 100–200 Hz; headphones and subwoofers go much lower.
• Your device and browser may resample, limit or process the sound, so this is not a calibrated measurement tool and cannot measure frequency response.
• This is not a hearing test or a medical device, and it makes no claims about "healing" frequencies. If you have concerns about your hearing, see a professional.