Tone Generator
A tone generator that sounds the moment you press Play: type or slide to any frequency, sweep 20 Hz to 20 kHz, or play white, pink and brown noise.
Ready to sound
0.1 to 600 — a length is a real question for a file and no question at all for a live tone.
Preset
A4 · concert pitch.
20 Hz to 20 kHz on a logarithmic track; the oscillator is retuned as it moves, never re-rendered.
Where it starts, and where it stays until you raise it.
How to use
- Pick a preset, or leave Source on Tone and type a Frequency or drag the slider. Switch Source to Sweep for a glide between two frequencies, or to Noise for white, pink or brown.
- Press Play, and Stop when you are done; it fades out rather than cutting off. To keep a copy, set Duration and press Download WAV.
About this tool
Type a number in hertz, press Play, and that frequency comes out of your speakers straight away. The box opens on 440, which is concert A, and takes anything from 20 Hz to 20 kHz, or to half your sound card's sample rate if that happens to be lower, since nothing above it can be played. The slider beside it is logarithmic, so the musical middle of the range gets most of its travel.
Change the number or drag the slider while the tone plays and the pitch follows, gliding over a few hundredths of a second instead of stopping and starting. Waveform is a row of four buttons. Sine is the pure one and the one to measure with. Square, triangle and sawtooth carry harmonics, and the browser's oscillator leaves out any harmonic the sample rate cannot carry, so near the top of the range a square quietly turns into a sine rather than filling up with false tones.
Source has three settings. Tone is one steady frequency. Sweep glides from one frequency to another over the seconds you give it, spending the same time on every octave, which is how you find where your hearing or a small speaker gives out. Noise swaps the frequency controls for a colour: white is flat and hissy, pink falls about 3 dB per octave and sounds balanced, brown falls faster and comes out as a low rumble.
Level starts at 12 percent on every visit and the sound fades in over a quarter of a second, so a high tone never arrives at whatever volume your last video left behind. The risky tones are the faint ones, because that is when people reach for the volume; set a comfortable level on the 1 kHz reference first and stay near it.
Download WAV is there for when you need a file rather than a sound. It writes the current settings for as long as Duration says, up to 600 seconds, as a mono 16-bit WAV at 44.1 kHz peaking around 80 percent of full scale, named for what it holds, like tone-440-sine-5s.wav.
Good to know
- Files stop at 600 seconds. Ten minutes of uncompressed mono WAV is already about 53 MB, so for an all-night noise session download a few minutes and loop it in whatever plays it back. Playing live has no time limit at all.
- What reaches your ears is up to the hardware. Most laptop and phone speakers make little or nothing below about 40 Hz, and plenty of adults hear nothing above 15 or 16 kHz, so silence at either end is usually the speaker or the listener rather than the tone.
Things people ask
Which waveform should I use to test a speaker?
Sine, and it isn't close. A sine wave holds one frequency and nothing else, so anything else you hear is the speaker, the room, or your own ears. The other three carry harmonics that muddy the exact thing you're listening for. Keep square and sawtooth for synth-flavoured sound design.
Is 440 here really 440?
The oscillator runs at exactly the number you typed, decimals included, with no snapping to the nearest note: 437.5 gives 437.5, and the note name beside the box is only a label. Where exactness stops is playback, since your sound card's clock and your speaker both get a vote.
Can it sweep, or play two tones at once?
It sweeps: switch Source to Sweep, say where to start, where to stop and how long to take, and the pitch climbs so every octave gets equal time. Two tones at once isn't built in, and neither is a left-right split for binaural work. Two browser tabs will layer two tones, though nothing keeps them in phase.
Which noise colour do people actually use for sleep?
Brown, mostly. Its energy sits low and it reads as a distant rumble rather than a hiss, which is easier to ignore for hours. Pink is the usual pick for concentration and for speaker testing, since it spreads roughly equal energy across each octave the way most music does. White is the harshest of the three and the one people give up on first.
How big does a ten-minute file get?
Around 53 MB. The WAV is uncompressed 16-bit mono at 44.1 kHz, which works out to roughly 5.3 MB a minute, and 600 seconds is the ceiling for a file. Download a couple of minutes and loop it if you want hours of the stuff.
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