697 Hz Wavelength

How Long Is a 697 Hz Wavelength?

A 697 Hz sound wave has a wavelength of 0.49 meters, 49.24 cm, 1.62 feet (1 feet and 7.39 inches) or 19.39 inches when traveling in air at 20°C (68°F).

The formula for the wavelenght is λ = c/f where:

  • c is the celerity (speed) of sound = 343.21 m/s or 1126.03 ft/s in air at 20°C (68°F).
  • f is the frequency = 697 Hz
which gives a wavelength λ of 0.49 meters, or 1.62 feet.

697 Hz Wavelength Depending on Temperature

The speed of sound in air depends on temperature. Here is how the wavelenght of a 697 Hz sound wave will vary according to temperature:

Temp (°C) Temp (°F) 697 Hz wavelength (cm)697 Hz wavelength (in)
-40-4043.914317.2891
-35-3144.382717.4735
-30-2244.846217.6560
-25-1345.304917.8366
-20-445.759118.0154
-15546.208718.1924
-101446.654118.3678
-52347.095218.5414
03247.532318.7135
54147.965318.8840
105048.394519.0530
155948.820019.2205
206849.241719.3865
257749.659919.5511
308650.074519.7144
359550.485819.8763
4010450.893720.0369

697 Hz Half Wavelength and Standing Waves

The half wavelength of a 697 Hz sound wave is 0.25 meters, 24.62 cm, 0.81 feet (0 feet and 9.69 inches) or 9.69 inches when travelling in air at 20°C (68°F).

Modes (or standing waves) will occur at 697 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:

  • n is a natural (positive integer greater than or equal to 1)
  • λ is the 697 Hz wavelength = 0.49 meters, or 1.62 feet in air at 20°C (68°F).

697 Hz Standing Waves Distances

n Distance (m) Distance (ft)
10.250.81
20.491.62
30.742.42
40.983.23
51.234.04

We typically don't treat rooms for standing waves above 300 Hz.

Given the relatively small 697 Hz half wavelength, you can treat your room by using thick acoustic foam. This will absorb frequencies as low as 250 Hz, and all the way up to 20,000 Hz.

How To Convert 697 Hz To ms

A Hz (Hertz) is a cycle (or period) per second.

Because a 697 Hz wave will ocillate 697 times per second, we can find the time of a single cycle (or period) with the formula p = 1/f where:

  • f is the frequency of the wave = 697 Hz

The result will be expressed in seconds, so let's multiply by 1000 to get miliseconds:

1 / 697 Hz * 1000 = 1.43 ms.