20 Hz
Bass (20–250 Hz) · D#0
Turn the volume down before you play. A pure tone is harder on the ears than music at the same level.
Standard band
A centre frequency of the standard one-third-octave bands used in noise measurement and speaker work.
Common value
A value that comes up often in searches and tests.
| Wavelength | 17.15 m |
|---|---|
| Period | 50 ms |
| Nearest note | D#0 |
| Off by | +49 cents |
| Audible | Yes |
| Harmonics | 40 Hz · 60 Hz · 80 Hz |
| One octave down | 10 Hz |
| One octave up | 40 Hz |
How to read this
- Hertz counts how many times the air vibrates per second. The bigger the number, the higher the pitch.
- Wavelength is the speed of sound (343 m/s at 20 °C) divided by the frequency. That makes 20 Hz seventeen metres long and 20 kHz under two centimetres.
- People hear roughly 20 Hz to 20 kHz, but the upper limit drops with age. Past about 15 kHz, some hear the tone and some do not.
- Hearing nothing does not mean the equipment is broken. Small speakers cannot reach the low notes, and for the high ones it is the ear that gives up first.
Frequently asked questions
Q. What does 20 Hz sound like?
It is a pure tone vibrating 20 times a second. It falls inside the range people hear, and the nearest musical note is D#0.
Q. What is the wavelength of 20 Hz?
17.15 m in air. Sound travels 343 metres per second through 20 °C air, so the wavelength is that distance divided by 20.
Q. What note is 20 Hz?
The nearest note is D#0, and it is 49 cents sharp. A semitone is 100 cents, so that is about 49% of a semitone away.
Q. I cannot hear 20 Hz — is something wrong?
Small speakers can barely produce bass this low. Try headphones or a larger speaker before assuming anything is broken.
Q. What are the harmonics of 20 Hz?
The whole-number multiples: 40 Hz, 60 Hz, 80 Hz. An octave up is double, 40 Hz; an octave down is half, 10 Hz.
Nearby frequencies
Frequency doubles for every octave, so closeness is measured in ratios, not differences.