SuperDevTools
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Online tone generator

Protect your ears and your equipment Always start at a low volume, then turn it up slowly. High-pitched tones and very loud bass can damage speakers and hearing. With headphones, lower the volume even more before starting a sweep.

440,00 Hz

Space bar: play or stop. Left and right arrows: ±1 Hz (with Shift: ±0.1 Hz). Up and down arrows: one semitone. Page Up and Page Down: one octave.

Shortcuts
Reference A

Several tones at once

Up to 4 oscillators at the same time, to hear beats or a chord. The first one is set above.

Channel test
Waveform
Spectrum

What you hear depends on your speakers or headphones: many cannot reproduce very low or very high frequencies. No sound starts without a click, and nothing is recorded or sent.

Play any frequency in your browser

This online tone generator plays a precise tone from 1 to 22,000 Hz: check speakers, test headphones, tune an instrument or demonstrate sound waves in class. The sound is computed on your device, nothing is recorded or sent, and nothing plays until you click. Read the box "Protect your ears and your equipment" first: the volume starts at 20% on every visit, so raise it slowly.

How to use it

  1. Pick a source: "Pure tone", "Sweep" or "Noise".
  2. Set the frequency with the logarithmic slider, the "Frequency (Hz)" box or the −1, −0.1, +0.1 and +1 buttons. "÷ 2" and "× 2" jump one octave.
  3. To hit a note, choose "Note" and "Octave". "Reference A (Hz)" is 440; 432 and 442 are one click away.
  4. Choose the "Waveform", then click "Play". The same button, or the space bar, stops the tone.
  5. Adjust "Volume", "Left / right balance" and, if needed, "Auto stop" (10 seconds to 1 hour).

Below the big number you see the nearest note, the offset in cents and the period. At 440 Hz: "A4, 0 cents off · period 2.273 ms"; at 445 Hz the offset becomes +19.6 cents.

The four waveforms

  • Sine: one frequency, no harmonics, the reference for measurements.
  • Square: the fundamental plus odd harmonics. At 1,000 Hz the "Spectrum" also shows 3,000, 5,000 and 7,000 Hz.
  • Triangle: the same harmonics, much weaker, so it sounds softer.
  • Sawtooth: every harmonic, a bright sound.

What people use it for

  • Speakers and subwoofers: play 30, 50 and then 100 Hz at a moderate level; buzzing points to a fault or something rattling. A logarithmic "Sweep" from 20 to 20,000 Hz over 10 seconds spends about one second per octave and reaches 632 Hz halfway.
  • Headphones: "Channel test" has "Left only", "Both" and "Right only".
  • Tuning: choose A, octave 4, and tune by ear. With A at 432 Hz, middle C (C4) drops from 261.63 to 256.87 Hz.
  • High school physics: at 100 Hz the period is 10 ms, at 1,000 Hz it is 1 ms.
  • Beats: "Beats 440 + 442 Hz" sets up two close tones; press play and you hear a throb twice per second. "C major chord" sets up C, E and G (up to 4 oscillators).

The range of human hearing

The usual figure is 20 Hz to 20 kHz for young ears. High frequencies fade with age, and many adults hear little above 14 to 16 kHz. This is a rough guide, not a hearing test. Many phone and laptop speakers also produce almost nothing below 100 to 200 Hz.

White, pink and brown noise

White noise has the same energy at every frequency: a bright hiss. Pink noise drops 3 dB per octave, so each octave carries the same energy; it is softer and used to balance speakers. Brown noise drops 6 dB per octave, like a distant rumble.

Hearing safety and tinnitus

Loud, long exposure tires the ear; US workplace rules start at 85 dBA averaged over 8 hours. Take breaks and never crank up headphones. If you hear ringing or buzzing (tinnitus), this tool is not a treatment: see a doctor, ideally an ENT specialist.

FAQ

Why can't I hear anything at 20 Hz or 18,000 Hz?

Your speakers cannot go that far, or your ears no longer pick it up. Try headphones at a moderate volume.

Can a tone damage my speakers?

Yes, if it is too loud, especially pure bass or treble. Start low and stop at the first odd noise.

Is the volume saved?

No. Other settings stay on your device, but the volume goes back to 20% on every visit.

Does the tone keep playing in another tab?

Yes, as long as the page stays open. "Auto stop" cuts it after the time you choose.