Sound level meters measure sound pressure in dB SPL absolute. DBA and dBC be adapted assessment filter curves the values.

There is no conversion formula from dB SPL to dBA or dBC, this is only executed using a single frequency measurement possible.

Level values are defined so that they are the same at 1kHz.

Hearing curve of 30 dB (at 50Hz) corresponds roughly to the human ear.

At low frequency signal with the A curve embellished always the result, so it is not an accurate description of the volume.

Hearing curve is linear over several octaves prospective only light filtering at under 10Hz and over 10kHz, thus suitable for measurements with a higher sound level.

Sound pressure (dB SPL) is a sound field which acts over the entire frequency spectrum.