20 Hz tone
The bottom edge of human hearing.
Volume first. Turn your device volume down before pressing play, then raise it slowly. Tones start quiet on purpose. Very low tones can damage small speakers and woofers if pushed hard. Stop if you hear rattling, distortion or cone slap.
What 20 Hz is used for
The conventional lower limit of hearing. Most small speakers and many headphones reproduce almost nothing here, so a 20 Hz tone is a quick test of true sub-bass extension.
| Period | 50.000 ms |
|---|---|
| Wavelength in air (20 °C) | 17.15 m |
| One octave down / up | 10 Hz / 40 Hz |
The generator above starts at 20 Hz. You can still move the slider to any other frequency, or open the full tone generator.
Questions people ask
Why can't I hear the 20 Hz tone?
Small speakers physically cannot move enough air at 20 Hz. Phones, laptops and most earbuds produce little or nothing this low; you need full-range speakers, good headphones or a subwoofer.
How long is one cycle of 20 Hz?
50.000 milliseconds. In room-temperature air the wavelength is about 17.15 metres.
Keep testing
- Tone generatorSine, square, triangle and sawtooth from 1 Hz to 22 kHz.
- Frequency sweepLogarithmic or linear sweeps over any range and duration.
- Subwoofer testBass tones from 10 Hz, a low sweep and a room-mode calculator.