1209 Hz
Midrange (250 Hz–4 kHz) · D6
Turn the volume down before you play. A pure tone is harder on the ears than music at the same level.
Phone keypad
The sound a phone key makes. Four row tones and four column tones form a grid, and each key sounds two of them at once.
1 · 4 · 7 · *
| Wavelength | 28.4 cm |
|---|---|
| Period | 827.1 µs |
| Nearest note | D6 |
| Off by | +50 cents |
| Audible | Yes |
| Harmonics | 2418 Hz · 3627 Hz · 4836 Hz |
| One octave down | 604.5 Hz |
| One octave up | 2418 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 1209 Hz sound like?
It is a pure tone vibrating 1209 times a second. It falls inside the range people hear, and the nearest musical note is D6.
Q. What is the wavelength of 1209 Hz?
28.4 cm in air. Sound travels 343 metres per second through 20 °C air, so the wavelength is that distance divided by 1209.
Q. What note is 1209 Hz?
The nearest note is D6, and it is 50 cents sharp. A semitone is 100 cents, so that is about 50% of a semitone away.
Q. I cannot hear 1209 Hz — is something wrong?
This band is comfortable for most equipment and most ears, so check the volume and the output device first.
Q. What are the harmonics of 1209 Hz?
The whole-number multiples: 2418 Hz, 3627 Hz, 4836 Hz. An octave up is double, 2418 Hz; an octave down is half, 604.5 Hz.
Nearby frequencies
Frequency doubles for every octave, so closeness is measured in ratios, not differences.