Play a sine, square, triangle or sawtooth tone at any frequency, or sweep between two
Processed in your browser. Nothing is uploaded. Updated on 25 Oct 2026.A pure tone is useful for testing speakers, tuning an instrument, or checking what you can still hear. Concert pitch is 440 Hz, and anything from a deep rumble to the top of hearing can be played. Choose sine, square, triangle or sawtooth, or sweep between two.
Leave Mode on Steady tone and pick a Waveform: Sine, Square, Triangle or Sawtooth.
Drag the Frequency slider, or type the number of hertz in the box under it.
Set your system volume first, then raise the Volume slider, which starts quiet on purpose.
Press Play the tone to hear it from your speakers; press Stop or Escape to end it.
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.
The volume opens at about three per cent of full scale, which is audible on almost any device and uncomfortable on none. Raising it past a level where a sustained tone becomes unpleasant puts a warning on screen before the tone starts rather than after it. A stop control is always on screen while anything is playing, and it is the first thing the keyboard reaches.
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.
A logarithmic sweep spends equal time in every octave, which is how hearing works and what an audio measurement wants. A linear sweep covers the same number of hertz every second, racing through the bass and crawling through the treble. Both are useful for finding a rattle: something that sounds fine on one note starts vibrating on another.
Type 440 into the frequency box, or press the concert A preset, then press play. Concert A is the reference an orchestra tunes to, and the note label beside the box confirms the pitch and shows how far any nearby frequency sits from it in cents.
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.
A logarithmic sweep spends the same amount of time in every octave, so 20 to 40 Hz takes as long as 10 to 20 kHz. Audio measurements use that shape because hearing works the same way. Choose a linear sweep only when you want a fixed number of hertz per second, such as when hunting a single resonance.
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.
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