Type a frequency in hertz and hear it, from 20 Hz to 20,000 Hz
Processed in your browser. Nothing is uploaded. Updated on 25 Oct 2026.Type a number in hertz and that exact pitch comes out of the speaker, anywhere from 20 up to 20,000. Useful for checking whether a buzz is mains hum at 50 or 60 hertz, for finding the note something is rattling at, or for producing the 1,000 hertz reference every audio measurement is quoted against. The nearest musical note and how far off it is in cents are shown beside the box.
The Frequency box already reads 1000 Hz, the reference tone audio levels are quoted against.
To hear another pitch, type any number from 20 to 20,000 in the hertz box; the nearest note shows beside it.
Press Play the tone, then raise the Volume slider slowly from its quiet start.
Press Stop, or the Escape key, when you have heard enough.
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.
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 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.
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On the related tools: Increase Audio Volume – Raise a quiet recording as far as it will go before anything starts to distort · Speed Up Audio – Make audio faster or slower without the chipmunk voice · Mic Test – See your voice on a live waveform and hear it played straight back.
In the collections Audio Tools · Audio Test Tools.