How to use the tone generator
- Type a frequency in hertz or drag the slider (it is logarithmic, like the way we hear pitch). The musical note is shown below the frequency.
- Choose the waveform and whether to play on both channels or only left or right, then press Play. Adjust the volume while it plays.
- Switch to Sweep to glide smoothly between two frequencies, for example to test speakers or find room resonances.
- Download the tone or sweep as a WAV file to use in other software.
Uses for a test tone
A pure sine tone at a known frequency is useful for tuning instruments (A4 = 440 Hz is concert pitch), testing speakers and headphones, checking left and right channels, finding rattles and resonances in a car or room, testing the frequency range of your hearing, and science lessons on sound and waves. Square, triangle and sawtooth waves contain harmonics and sound buzzier; they are handy for demonstrating timbre. The semitone buttons move by exactly one equal-tempered step (a factor of 21/12 ≈ 1.0595), and the octave buttons halve or double the frequency.
Most speakers cannot reproduce frequencies below about 40–60 Hz, and laptop and phone speakers struggle below 100–200 Hz, so a silent low tone usually means the speaker has reached its limit, not that the generator stopped. Adult hearing typically ends somewhere between 14 and 18 kHz. Sound is generated in your browser with the Web Audio API; nothing is streamed or recorded. Keep the volume moderate: protect your ears and your tweeters.
What frequency is middle C?
About 261.63 Hz (C4) with A4 tuned to 440 Hz.
Why can't I hear very low or very high tones?
Small speakers cannot reproduce deep bass, and hearing of high frequencies declines with age.
Can I play two tones at once?
Open the page in a second tab to play another tone, for example to hear beat frequencies.