The sound pressure level (SPL) is a logarithmic figure stated in decibels [dB] to describe the intensity of the sound. As the SPL is a technical figure, correlations to the perceived volume is only possible in part. To quantify the perceived volume, assessed sound pressure levels (A,B and C) are used. The A-assessment - dB(A), which is the most similar to the frequency response of the human ear, is therefore generally used for stating the SPL.
When the sound pressure level is raised by 10 dB, this is subjectively perceived as a doubling of the volume.