How Long Is a 9 Hz Wavelength?
A 9 Hz sound wave has a wavelength of 38.13 meters, 3813.5 cm, 125.11 feet (125 feet and 1.38 inches) or 1501.38 inches when traveling in air at 20°C (68°F).
The formula for the wavelenght is λ = c/f where:
cis the celerity (speed) of sound = 343.21 m/s or 1126.03 ft/s in air at 20°C (68°F).fis the frequency = 9 Hz
λ of 38.13 meters, or 125.11 feet.
9 Hz Wavelength Depending on Temperature
The speed of sound in air depends on temperature. Here is how the wavelenght of a 9 Hz sound wave will vary according to temperature:
| Temp (°C) | Temp (°F) | 9 Hz wavelength (m) | 9 Hz wavelength (ft) |
|---|---|---|---|
| -40 | -40 | 34.0092 | 111.5786 |
| -35 | -31 | 34.3719 | 112.7687 |
| -30 | -22 | 34.7309 | 113.9464 |
| -25 | -13 | 35.0861 | 115.1120 |
| -20 | -4 | 35.4378 | 116.2659 |
| -15 | 5 | 35.7861 | 117.4085 |
| -10 | 14 | 36.1310 | 118.5400 |
| -5 | 23 | 36.4726 | 119.6609 |
| 0 | 32 | 36.8111 | 120.7714 |
| 5 | 41 | 37.1465 | 121.8717 |
| 10 | 50 | 37.4789 | 122.9622 |
| 15 | 59 | 37.8083 | 124.0431 |
| 20 | 68 | 38.1350 | 125.1147 |
| 25 | 77 | 38.4588 | 126.1772 |
| 30 | 86 | 38.7799 | 127.2308 |
| 35 | 95 | 39.0984 | 128.2757 |
| 40 | 104 | 39.4144 | 129.3122 |
9 Hz Half Wavelength and Standing Waves
The half wavelength of a 9 Hz sound wave is 19.07 meters, 1906.75 cm, 62.56 feet (62 feet and 6.69 inches) or 750.69 inches when travelling in air at 20°C (68°F).
Modes (or standing waves) will occur at 9 Hz in rooms where two opposing walls (axial mode), edges (tangential mode) or corners (oblique mode) are spaced by a distance d = nλ/2 where:
nis a natural (positive integer greater than or equal to 1)λis the 9 Hz wavelength = 38.13 meters, or 125.11 feet in air at 20°C (68°F).
9 Hz Standing Waves Distances
| n | Distance (m) | Distance (ft) |
|---|---|---|
| 1 | 19.07 | 62.56 |
| 2 | 38.13 | 125.11 |
| 3 | 57.20 | 187.67 |
| 4 | 76.27 | 250.23 |
| 5 | 95.34 | 312.79 |
Given the relatively large 9 Hz half wavelength, standing waves will occur at that frequency in small listening rooms.
You can try to minimze the room modes at 9 Hz by trying different speaker positions, listening positions or by placing bass traps. These can absorb frequencies as low as 63 Hz.
How To Convert 9 Hz To ms
A Hz (Hertz) is a cycle (or period) per second.
Because a 9 Hz wave will ocillate 9 times per second, we can find the time of a single cycle (or period) with the formula p = 1/f where:
fis the frequency of the wave = 9 Hz
The result will be expressed in seconds, so let's multiply by 1000 to get miliseconds:
1 / 9 Hz * 1000 = 111.11 ms.