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Toolvica

Tone Generator

Log slider 20–20000 Hz, fine ±0.1/±1, ×½/×2, sweep log/linear, 4 waves, note picker, dBFS, shareable link — in your browser.

440 Hz

A4 · +0 cents · 2.27 ms · -9.5 dBFS

Tap to start and stop the tone ·

20 – 20000 · log scale
Sweep · 20 Hz → 20 kHz · 20s

Glides smoothly for speaker & hearing tests. Playing sweep overrides manual frequency until stopped.

⚠️ Start with low volume. The dBFS readout is a signal level, not actual loudness — what reaches your ears depends on your device and headphone volume. Increase gradually, especially with headphones.

What this Tone Generator offers

Log slider 20–20000 Hz with fine tune, octave, sweep and share — four waveforms, note picker, dBFS metering and safety notice. Web Audio synthesis, fully local.

  • Four waveforms (sine/square/sawtooth/triangle) with distinct harmonics
  • Log slider 20–20000 (0.1 Hz), number input, note picker, presets + fine ±0.1/±1 and ×½/×2 octave, keyboard ←→
  • Nearest-note + cents, period and dBFS readout — reverse tuner style
  • Log/linear sweep 20 Hz→20 kHz (20s), shareable link ?freq=&wave=&vol=, volume capped, fully local

How to use

  1. Set frequency via log slider (20–20000), 0.1 Hz number input, note picker, presets, fine ±0.1/±1 or ×½/×2 octave — or ←→ / Shift+←→ / Ctrl+←→ keys.
  2. Choose sine/square/sawtooth/triangle, set volume (dBFS shown), and pick sweep Log/Linear 20s if needed.
  3. Press Play (or Space) to sustain — readout shows nearest note + cents, period and dBFS. Use Sweep to glide 20 Hz→20 kHz.
  4. Press Stop or Space again. Copy shareable link (?freq=&wave=&vol=) to share. Keep volume low — see safety note.

What is a tone generator?

A tone generator synthesizes a steady waveform at an exact frequency through the Web Audio API. Sine waves hold one pure pitch, while square, sawtooth and triangle add harmonics above it.

Musicians use it to test speakers and headphones, tune by ear against a reference, check room resonances, and calibrate equipment. Producers use known frequencies to verify monitoring chains.

At 440 Hz you hear concert A, at 261.63 Hz middle C. Doubling frequency raises one octave, so 880 Hz is A5. Keep volume low at first, especially with headphones and high frequencies.

Features

Four waveforms

Sine for pure reference, square and sawtooth for rich harmonics, triangle in between.

Log slider + fine & octave

Log 20–20000 Hz (0.1 Hz), fine ±0.1/±1, ×½/×2 octave, keyboard ←→/Shift/Ctrl and presets Bass 60/C4/A4/A5/1k.

Nearest note + dBFS readout

Every frequency maps to closest note with cents, period and dBFS (−∞…0), like a reverse tuner with level metering.

Sweep, share & safe

Log/linear sweep 20 Hz→20 kHz (20s), shareable link ?freq=&wave=&vol=, dBFS, 30% safe default, fully local, no upload.

Tips

Start quiet

Begin near zero volume and raise slowly. Sustained high frequencies fatigue ears fast.

Use sine for tuning

Sine has no harmonics to confuse the ear. Play A4 and tune your string to zero beating.

Test both ears

Pan check with mono tone in each ear to spot dead headphone drivers.

FAQ

What frequency range works?
20 to 20000 Hz, the nominal human hearing range. Most laptop speakers roll off below 100 Hz and above 15 kHz, so use headphones for extremes.
Which waveform should I use?
Sine for tuning and testing, square or sawtooth to stress speakers and hear harmonics, triangle as a softer middle ground.
Is it safe for headphones?
Yes at sensible volume. Start low, avoid long loud high-frequency exposure, and stop if anything hurts.
Can I play a specific note?
Yes. Pick note and octave in the picker and the exact frequency is set, with cents readout showing any offset.
Does it work offline?
Yes. Tones are synthesized live with Web Audio after the page loads. No files or network needed.
Why do I see a nearest note?
Every frequency maps to the closest twelve-tone note with cents deviation, so arbitrary values like 445 Hz read as near A4 plus cents.

References

1. Web Audio API — MDN. developer.mozilla.org/Web/API/Web_Audio_API

2. Twelve-tone equal temperament with A4 reference pitch.

For practice and education. Timing accuracy depends on device performance and browser audio scheduling. For critical recording, compare with a hardware metronome.