To establish a standard set of letter symbols for quantities used in the science and technology of acoustics: also to establish standard abbreviations for a number of acoustical levels and related measures that are in common use. The science and technology of acoustics include sound, ultrasound, and infrasound in all media: gases, especially air; liquids, especially water; and solids are examples of media with which acoustics is concerned. There are many specialties in acoustics, a few of which are: speech, hearing, music, noise control, vibration, shock, and sonar.