Sound pressure measurement in decibels. In decibels, 20 times the logarithm of the ratio of the pressure of a sound to the reference pressure, which must be explicitly stated. Also, the pressure of an acoustic wave stated in terms of dynes per square centimeter or microbars.
"Thanks for transferring my wife's treasured childhood 12 sided 78 rpm album to CD and cassette tape. The quality is outstanding. It is better than I remember these old records sounding. I am also pleased with the way the CD is labelled and reproduction of the original album cover art work on the CD box. We had almost given up ever hearing this ..."