Play any frequency, read the note, sweep your room
A pure-tone generator from 20 Hz to 20 kHz with four waveforms. See the musical note for any frequency, sweep the whole spectrum to find room resonances, and pan left or right to test each speaker. Runs instantly, no signup.
How to use it
Four steps from open tab to a tone in the room.
1. Set your frequency
Drag the slider, type an exact number, or tap a preset below. The big readout shows the frequency and its nearest musical note as you move.
2. Pick a waveform
Sine is the pure tone for testing. Square, saw and triangle add harmonics, useful for ear training on timbre. Leave it on sine if you are diagnosing speakers or a room.
3. Choose the channel
Keep it on Both for normal use, or switch to Left only or Right only to confirm each speaker is wired and working before you mix.
4. Start quiet, then play or sweep
Turn the volume low, hit Play Tone, and raise it gently. To hunt room resonances, press Sweep and listen for notes that boom or disappear as it climbs.
One-tap test tones
The frequencies producers reach for most. Tap one to play it instantly.
What a tone generator is actually for
A pure tone is the most useful diagnostic signal in audio. Four jobs it does in seconds.
Test speakers and subs
Sweep the low presets to find where your monitors give up and the sub takes over. If 40 Hz rattles something in the room, you have found a problem your mixes were fighting silently.
Find room resonances
Sweep slowly through 60 to 300 Hz at moderate volume and listen for notes that suddenly boom or vanish as the room joins in. Those are the frequencies lying to you in every mix.
Tune and train your ear
440 Hz is concert-pitch A4, and the note readout names whatever frequency you dial. Compare the waveforms at one pitch to hear how harmonics change timbre, which is half of what synthesis is.
Check your hearing range
The 10 kHz and 15 kHz presets are the honest ones. Most adults lose the top octave over time, and knowing where your hearing rolls off matters when you are the one making EQ calls up high.
Why the same level sounds louder up high
Your ears are not flat. They peak in sensitivity around 3 to 4 kHz, which is why a 4 kHz tone feels far louder than a 100 Hz tone at the same volume, and why you must start quiet.
Found a problem? Here is the fix.
If a sweep exposed booming low notes or a dead spot, the room is the cause. These help next.
Questions, answered
Is this tone generator free?
Yes, unlimited use and no signup. The tone is synthesised live in your browser with the Web Audio API, so nothing is downloaded or streamed.
Why does 4 kHz sound louder than 100 Hz at the same volume?
Human hearing peaks in sensitivity between roughly 2 and 5 kHz, as the curve above shows. Equal signal level is not equal loudness, which is exactly why mixes need checking across the spectrum, and why the volume warning is serious.
What is the difference between the waveforms?
Sine is the pure frequency with no harmonics. Triangle adds soft odd harmonics, square adds strong odd harmonics, and saw contains every harmonic, making it the brightest. For testing use sine; to train your ear on timbre, compare all four at one pitch.
What does the note readout show?
It converts the current frequency to the nearest musical note and octave, and shows how many cents sharp or flat it is. Dial 440 Hz and you will see A4; move off it and watch the cents shift.
Can I damage my speakers with low frequencies?
At high volume, yes. Small speakers can be pushed past their excursion limits by sustained sub-bass. Test low frequencies at modest volume and stop if you hear distortion.
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