§ 97.10  DEFINITIONS.
   For the purpose of this chapter, the following definitions shall apply unless the context clearly indicates or requires a different meaning.
   A WEIGHTED SOUND LEVEL.  The sound pressure level in decibels as measured on a sound level meter using the A-weighted network.  The level so read is designated dB(A) and DBA or dba.
   AMBIENT SOUND LEVEL.  The all-encompassing sound associated with a given environment, being a composite of sounds from many sources.  For the purpose of this chapter, AMBIENT SOUND LEVEL is that level which is exceeded 50% of the time during an observation period of not less than ten minutes, excluding impulsive sounds and the alleged offensive sound and sounds not normally associated with a given environment, such as construction noises, lawn mowers and railroad trains.
   DAY.  Refers to the hours between 7:00 a.m. and 10:00 p.m.
   DECIBEL.  A logarithmic (dimension- less) unit of measure often used in describing the amplitude of sound.  Decibel is denoted as dB or db.
   EMERGENCY.  Any occurrence or set of circumstances involving actual or imminent physical injury or property damage which demands immediate action.
   EMERGENCY VEHICLE.  Any motor vehicle as defined in F.S. § 843.16 as currently enacted or as amended from time to time.
   EMERGENCY WORK.  Any work performed for the purpose of preventing or alleviating the physical trauma or property damage threatened or caused by an emergency.
   IMPULSIVE SOUND.  Sound of short duration, usually less than one second, with an abrupt onset and rapid decrease.  Examples of sources of impulsive sound include explosions and discharge of firearms.
   LEVEL, FIFTY PERCENTILE.  The A-weighted sound pressure level that is exceeded 50% of the time in any observation period.  It is denoted as 150.
   LEVEL, TEN PERCENTILE.  The A-weighted sound pressure level that is exceeded 10% of the time in any observation period.  It is denoted as 110.
   NIGHT.  Refers to the hours between 10:01 p.m. and 6:59 a.m.
   NOISE DISTURBANCE.  Sounds that are not measurable or may not exceed the sound standards but which, because of its volume level, duration or character, annoys, disturbs, injures or endangers the comfort, health, peace or safety of a reasonable person of ordinary sensibilities.
   OBSERVATION PERIOD.  The time interval during which acoustical data and facts are obtained.  Unless otherwise indicated, the observation period must be a minimum of ten minutes.
   SOUND.  An oscillation in pressure, particle displacement, particle velocity or other physical parameter, in a medium with internal forces which cause compression and rarefaction of that medium.  The description of sound may include any characteristic of that sound, including duration, intensity and frequency.
   SOUND LEVEL.  The A-weighted sound pressure level measured with fast response using a sound level meter.
   SOUND LEVEL METER.  An instrument used to measure sound pressure levels.  The output meter reads sound pressure levels when properly calibrated (yearly) and the instrument is of a type 2 or better, as specified in the American National Standard Institute publication S1.4-1971, or its successor publications.
(Ord. 94-32, passed 4-5-94)