31.5 Hz
Bass (20–250 Hz) · B0
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.
| Wavelength | 10.89 m |
|---|---|
| Period | 31.75 ms |
| Nearest note | B0 |
| Off by | +35 cents |
| Audible | Yes |
| Harmonics | 63 Hz · 94.5 Hz · 126 Hz |
| One octave down | 15.75 Hz |
| One octave up | 63 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 31.5 Hz sound like?
It is a pure tone vibrating 31.5 times a second. It falls inside the range people hear, and the nearest musical note is B0.
Q. What is the wavelength of 31.5 Hz?
10.89 m in air. Sound travels 343 metres per second through 20 °C air, so the wavelength is that distance divided by 31.5.
Q. What note is 31.5 Hz?
The nearest note is B0, and it is 35 cents sharp. A semitone is 100 cents, so that is about 35% of a semitone away.
Q. I cannot hear 31.5 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 31.5 Hz?
The whole-number multiples: 63 Hz, 94.5 Hz, 126 Hz. An octave up is double, 63 Hz; an octave down is half, 15.75 Hz.
Nearby frequencies
Frequency doubles for every octave, so closeness is measured in ratios, not differences.