§ 92.21 DEFINITIONS.
   For the purpose of this subchapter, the following definitions shall apply unless the context clearly indicates or requires a different meaning. All terminology used in this subchapter, not defined below, shall be in conformance with applicable publications of the American National Standards Institute (ANSI).
   A-WEIGHTED SOUND LEVEL. The sound pressure level in decibels as measured on a sound level meter using the A-weighting network. The level so read is designated dB(A).
   AMBIENT NOISE LEVEL. The composite of noise from all sources near and far. In this context, the AMBIENT NOISE LEVEL constitutes the normal or existing level of environmental noise at a given location when sound is not being electronically amplified at a location.
   EXCEEDANCE LEVELS L10 AND L1. The A-weighted sound levels which exceed 10% and 1%, respectively, of the specified measurement period.
   INTRUSIVE NOISE. Noise which intrudes over and above the existing ambient noise at a given location. The relative intrusiveness of a sound depends upon its amplitude, duration, frequency, time of occurrence, and tonal or information content as well as the prevailing ambient noise level.
   NOISE. Any sound which annoys or disturbs human beings or which causes, or tends to cause, an adverse psychological or physiological effect on human beings.
   SOUND AMPLIFICATION EQUIPMENT. Any device for the amplification of the human voice, music, instruments, or any other sound associated with mass assemblies.
   SOUND LEVEL METER. An instrument, including a microphone, an amplifier, an output meter or recording device, and frequency weighting network for the measurement of sound level, which satisfies the requirements for Type S2A meters, as set forth in the American National Standards Institute specifications for sound level meters, S1.4-1971, or the most recent revision thereof.