Helmholtz number
The Helmholtz number (symbol: He ), named after Hermann von Helmholtz , describes the ratio of a characteristic length in acoustics , e.g. B. the dimensions of a speaker membrane, the wavelength of the sound waves . It can also be formed from the product of a characteristic length and the wave number .
The individual symbols stand for the following quantities :
- λ = wavelength of the sound waves ,
- L , r = characteristic lengths (e.g. the height of an obstacle or the radius of a sound-conducting pipe ),
- k = wave number .
The Helmholtz number can be used to describe a large number of acoustic processes: For example, if the Helmholtz number is small, the sound is badly emitted; if the Helmholtz number is large, sound is effectively radiated.