How to use the tone generator
Press Play, then drag the slider or type a frequency. The buttons move the tone by a hertz, a semitone or an octave, and the note name shows how far you are from the nearest note in cents (hundredths of a semitone). Every tone you set gets its own link, so you can send someone exactly 432 Hz or a 17 kHz test tone.
Sine, square, triangle and sawtooth
A sine wave is a single frequency with no overtones: the purest sound there is, and the one used for hearing tests and ear training. Square, triangle and sawtooth waves add harmonics on top of the same fundamental, which is why they sound brighter and buzzier even at the same pitch.
Frequencies of musical notes
In standard tuning, A4 is 440 Hz and every octave doubles the frequency. Each semitone multiplies it by the twelfth root of two, about 1.0595.
| Octave | C | A |
|---|---|---|
| 1 | C1 · 32.70 Hz | A1 · 55.00 Hz |
| 2 | C2 · 65.41 Hz | A2 · 110.00 Hz |
| 3 | C3 · 130.81 Hz | A3 · 220.00 Hz |
| 4 | C4 · 261.63 Hz | A4 · 440.00 Hz |
| 5 | C5 · 523.25 Hz | A5 · 880.00 Hz |
| 6 | C6 · 1046.50 Hz | A6 · 1760.00 Hz |
| 7 | C7 · 2093.00 Hz | A7 · 3520.00 Hz |
Common uses
- Tuning an instrument by ear to A4 = 440 Hz
- Testing speakers and headphones, and finding the low end of a subwoofer
- Finding the frequency of a ringing noise or a hum (mains hum is 50 Hz or 60 Hz depending on country)
- Ear training: learning what pitches and intervals sound like without the colour of an instrument
Popular tones
20 Hz tone · 40 Hz tone · 50 Hz tone · 60 Hz tone · 100 Hz tone · 256 Hz tone · 432 Hz tone · 440 Hz tone · 528 Hz tone · 1 kHz test tone · 8 kHz tone · 15 kHz tone · 17.4 kHz mosquito tone · 20 kHz tone
Questions
Is it safe to listen to test tones?
At a comfortable volume, yes. Start quiet: pure tones, especially very high or very low ones, can sound quieter than they are, and loud tones on headphones can damage hearing.
Why can't I hear 20,000 Hz?
Most adults can't. High-frequency hearing declines gradually with age, and many phone speakers and headphones can't reproduce the top of the range either. Try the hearing test to find your own limit.
What frequency is middle C?
Middle C (C4) is 261.63 Hz in standard tuning, where A4 is 440 Hz.
Is 432 Hz better than 440 Hz?
432 Hz is simply a slightly lower tuning, about a third of a semitone below 440 Hz. Claims that it has special healing or calming effects aren't supported by good evidence.
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