Low frequency

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Low frequency ( NF ) ( English audio frequency , AF , and low frequency ) is a technical term for periodic processes (such as vibrations or waves ) with a frequency between 3 Hz and 30 kHz. For certain types of vibration, low frequency is more narrowly or further defined.

  1. The frequency range of audible sound waves extends from 16 to 20,000  Hz and is also known as the audio frequency.
  2. In the electromagnetic spectrum, the low frequency ranges from 3 Hz to 30 kHz and is divided into the frequency bands ELF , SLF , ULF and VLF , the latter also being called longest wave or myriameter waves .
  3. In the area of electromagnetic environmental compatibility , frequencies between 1 Hz and 100 kHz are assigned to the low frequency.
  4. The regulation on electromagnetic fields defines the low frequency range up to 9 kHz.
  5. In resistance welding , the low frequency range includes welding machines operated with 50 Hz alternating current. Anything above that is medium frequency (1-4 kHz) or high frequency (> 20 kHz).

Examples

Hi-fi speakers cover a frequency range from around 30 Hz to 20,000 Hz. The normal human voice is in the fundamental tones between about 250 Hz and 1,100 Hz, guitar music ranges from about 60 Hz to 2,000 Hz.

Standard frequencies for acoustic measurements according to DIN 45401 or DIN ISO 266: 1997 are fixed frequencies at which measurements in the fields of acoustics and electroacoustics are to be carried out.

Demarcation

  • Tones below 16 Hz are called infrasound .
  • Tones above about 20 kHz are called ultrasound .
  • In the case of electromagnetic oscillations and waves, frequencies above 30 kHz are generally referred to as high frequencies .
  • Within the electromagnetic spectrum , the English term "low frequency" (LF) exclusively describes a certain frequency band of electromagnetic waves, the long wave range (LW) from 30 kHz to 300 kHz.

See also

Web links

Individual evidence

  1. Guidelines for limiting exposure to time-varying electrical, magnetic and electromagnetic fields (up to 300 Ghz). (pdf, 392 kB) ICNIRP, 1998, p. 75 , accessed on June 17, 2020 .