Hypersonic
Hypersonic is sound with frequencies above about 1,000 MHz (= 1 GHz ). It is therefore a sub-range of ultrasound (frequencies from around 16 kHz). The limit of 1 GHz was previously specified in DIN 1320 (acoustics - terms). In the current version of DIN 1320: 2009, however , the term hypersonic is no longer used.
Because of the very high attenuation in fluids at these frequencies, the propagation of hypersonic in solids is of particular importance ( structure-borne noise ). Both longitudinal and transverse waves as well as surface waves can occur there.
At extremely high frequencies, sound in crystalline solids is described by phonons , i.e. quasiparticles of the lattice vibrations ; this also results in the upper frequency limit, which, depending on the material, is in the range of approx. 10 THz .
Individual evidence
- ↑ Beuth Verlag: Information on the DIN 1320: 2009-12 standard , see “Introductory article ”, first bullet point
