Generate a steady test frequency for speakers, headphones or instruments
Processed in your browser. Nothing is uploaded. Updated on 25 Oct 2026.Engineers reach for a steady test frequency constantly: to find which driver in a speaker is buzzing, to check that a cable passes signal, to set a crossover, or to hear whether a room has a resonance sitting on one note.
Pick a chip under Presets, such as 60 Hz mains hum or 8 kHz treble, or set your own Frequency.
Waveform starts on Sine, the cleanest test signal; the note beside it says what each waveform is for.
Press Play the tone and raise Volume a little at a time while you listen to the speaker.
Change the frequency while it plays to track down a buzz, then press Stop.
Four waveforms are offered, each with a short note on what it is for, and the volume starts low enough that nothing is ever a surprise when you press play.
This tone generator plays a steady tone at any frequency between 20 Hz and 20,000 Hz, in four waveforms, and can sweep between two frequencies over a time you set. The sound is produced by the Web Audio oscillator built into your browser, so nothing is downloaded, nothing is recorded, and no file is involved anywhere.
Two settings deserve particular care. A tone above roughly 16 kHz is inaudible to many adults while still being loud, so it is possible to leave one playing at a volume you would never have chosen if you could hear it; the page says so when you cross that line. And a square or a sawtooth carries far more energy than a sine at the same amplitude, so both are quietened automatically to match, which is why switching waveform does not jump in loudness.
A sine is one pure frequency and nothing else, which is what hearing checks, tuning and speaker testing want. A square adds every odd harmonic and sounds hard and buzzy. A triangle adds the same harmonics but they fade quickly, so it sits between the two. A sawtooth contains every harmonic and is the brightest and harshest of the four. Above about 5 kHz the harmonics fall outside hearing, so all four begin to sound alike.
The rest of the article, and all 6 questions about Tone Generator, are on the Tone Generator page.
Sustained loud sound damages hearing whatever produces it, and headphones remove the distance that normally protects you. The generator opens at about three per cent of full scale for that reason and warns before any setting loud enough to be uncomfortable. Set your system volume low first, then raise it gradually.
Laptop and phone speakers are too small to move enough air at low frequencies, so most produce almost nothing below 150 Hz and nothing useful below 60 Hz. What you hear at those settings is usually harmonics or the case rattling. Headphones or a proper speaker will reach much lower.
A sine wave is a single frequency with no harmonics, so it sounds smooth and pure. A square wave adds every odd harmonic above the fundamental, which makes it buzzy and noticeably louder at the same amplitude. Both are quietened to match here, so switching between them does not jump in volume.
No microphone is used and no permission is requested. The tone is synthesised by your browser's audio engine and played straight to the speakers. Nothing is recorded, nothing is saved, and no audio leaves the page at any point.
Still stuck? Ask about Tone Generator and anybody who knows can answer. No account needed.
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