This International Standard specifies: a) the typical application for a permanently installed sound-monitoring system around an airport; b) performance specifications for instruments, and requirements for their unattended installation and operation, so as to determine continuously monitored sound pressure levels of aircraft sound at selected locations; c) requirements for monitoring the sound of aircraft operations from an airport; d) requirements for the quantities to be determined to describe the sound of aircraft operations; e) requirements for data to be reported and frequency of publication of reports; f) a procedure for determining the expanded uncertainty of the reported data in accordance with ISO/IEC Guide 98-3. This International Standard does not provide - a method for confirming or validating predicted sound contours; - a method for determining, validating or confirming aircraft noise certification data; - a method for describing the sound generated by aircraft while on the ground (including ground movements and the use of auxiliary power units), except while on the runway after start of roll for departures and between touchdown and leaving the runway for arrivals.