Online tone generator: 20 Hz – 12 kHz test tones
Generate a pure test tone at any frequency from 20 Hz to 12 kHz, with a choice of sine, square, triangle or sawtooth waveforms. The tone is synthesised locally with the Web Audio API — nothing is downloaded or uploaded and no microphone access is needed. Turn your volume down before pressing Play: a sustained pure tone is louder than it seems, especially on headphones.
What you can do with it
- Check speaker and headphone frequency response. Start at 20 Hz and slide the frequency up slowly. Note where the tone first becomes clearly audible: small laptop speakers usually wake up around 100–200 Hz, decent bookshelf speakers around 50–60 Hz, and a subwoofer should reproduce 20–30 Hz. At the top end, listen for where the tone disappears or turns harsh — that reveals the driver's practical limits.
- Find rattles and resonances. A slow sweep through the bass range makes loose speaker grilles, desk panels and shelf ornaments buzz at their resonant frequency, so you can locate and silence them. This is the classic way to track down "something vibrates when music plays".
- Test each ear and your upper hearing limit. Play a quiet tone and raise the frequency until you no longer hear it. Young adults typically hear up to 17–20 kHz; the limit falls naturally with age. Keep the volume low and treat this as a curiosity check, not a medical hearing test — see an audiologist for a real audiogram.
- Diagnose audio equipment. A steady sine at 440 Hz or 1 kHz is the standard signal for checking cables, mixers, amplifiers and Bluetooth links for dropouts, crackle, channel imbalance or distortion — much easier to judge than music.
- Tune an instrument. 440 Hz is concert pitch A4. Guitar strings from low to high are roughly E2 82.4 Hz, A2 110 Hz, D3 146.8 Hz, G3 196 Hz, B3 246.9 Hz and E4 329.6 Hz.
Choosing a waveform
A sine wave contains a single frequency and is the right choice for response and hearing checks. Square and sawtooth waves add strong harmonics — they sound buzzy, help you perceive very low fundamentals on small speakers, and stress-test amplifiers for distortion. Triangle sits in between: softer harmonics, a mellow, flute-like tone.
Testing the rest of the chain? Check playback with the left/right speaker test and your input with the microphone test.
FAQ
What frequency should I test my speakers with?
Sweep slowly from 20 Hz upward and note where the tone becomes audible. Laptop speakers: expect ~100–200 Hz. Bookshelf speakers: ~50–60 Hz. Subwoofers: 20–30 Hz. For the treble end, sweep up until the tone vanishes.
Up to what frequency should I be able to hear?
Most young adults hear up to about 17–20 kHz, and the ceiling drops with age — many people over 40 top out between 12 and 15 kHz. Hardware matters too: some speakers roll off before your ears do. This is an informal check, not a hearing exam.
Which waveform should I use?
Sine for clean measurements and hearing checks; square or sawtooth to make low frequencies more audible on small speakers and to test for distortion; triangle for a softer harmonic-rich tone.
Is anything uploaded?
No. The tone is generated locally in your browser with the Web Audio API. This page never accesses your microphone, and nothing is recorded or uploaded.