What is considered a high-frequency?

High frequency sound is sound of which the frequency lies between 8 and 20 kHz . High frequency sound with a frequency over 16 kHz can hardly be heard, but it is not completely inaudible. High frequency sound and even ultrasound in the lower frequency zone (up to 24 kHz) can be audible if the sound level is high enough.

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Is ELF radiation hazardous?

It’s not clear that exposure to ELF radiation is harmful , but there are things you can do to lower your exposure if you are concerned. Your exposure is based on the strength of the ELF radiation coming from each source, how close you are to each, and how long you spend in the field.18 Nis 2017

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