Sweep smoothly between two frequencies over a time you choose
Processed in your browser. Nothing is uploaded. Updated on 25 Oct 2026.Sweeping is how a rattle, a buzz or a resonance gives itself away: something that sounds fine on one note starts vibrating on another, and a slow sweep walks through every note in between. Choose the two frequencies and how long the trip should take, and pick a logarithmic sweep, which spends equal time in every octave, or a linear one, which covers the same number of hertz every second.
Mode is already set to Sweep; type the start and end frequencies in From and To.
Type how long the sweep should take in Seconds.
Choose Logarithmic for equal time in every octave, or Linear for the same hertz every second.
Press Play the sweep; the frequency it has reached shows on screen until it ends or you press Stop.
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.
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.
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.
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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On the related tools: Mic Test – See your voice on a live waveform and hear it played straight back.
In the collections Audio Tools · Audio Test Tools.