APPENDIX A: SCIENTIFIC DEFINITIONS
   A-WEIGHTED SOUND LEVEL. The sound pressure level of a sound measured through an A- weighting filter network. The level read is designated dB(A) or dBA.
   DECIBEL (dB). The unit used for comparing the sound pressure level of a sound to the sound pressure level of a reference sound having a sound pressure of 20 micropascals.
   FREQUENCY. The number of periodic oscillations, vibrations or waves per unit time (usually one second).
   HERTZ (HZ). The unit used for measuring the frequency of a sound.  The number of hertz is the number of cycles per second of a periodic sound pressure wave.
   OCTAVE BAND. A portion of the entire sound frequency spectrum contained between two frequencies A and B such that A = 2B.
   SOUND PRESSURE LEVEL. Twenty times the logarithm (base 10) of the ratio of the measured sound pressure to a reference pressure of 20 micropascals. The sound pressure level is expressed in decibels (dB).
   SPL = 20 LOG10   sound pressure A
               sound pressure B
   Sound pressure A = measured sound pressure
   Sound pressure B = reference sound pressure (20 micropascals)