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The test procedure which is to be followed in the event that an evaluation of the noise level reduction (NLR) of the completed building is required by the building official is provided in this section. Alternates to this procedure may be submitted to the building official prior to the initiation of a field test. Field tests should not be undertaken pursuant to the provisions of the amendment prior to the approval of such alternates by the building official.
(A) Interior sound level. The interior sound level shall be measured within a habitable room or rooms of the building. The room or rooms nearest to the aircraft noise source(s) shall be selected. Indoor measurements shall be made at a point five feet above the floor of the room or rooms, three feet from the window nearest the aircraft noise source(s), with curtain (if any) fully opened. The measurement position shall be midway between the sides of the window. Heaters, air conditioners and other equipment shall be inoperative during the measurement period. Tests shall be conducted in rooms with carpets and furnishings.
(B) Exterior sound level. The exterior sound level shall be measured at location away from the building (at least ten feet from any sound reflecting surface). The location should be in a direction from the building nearest to the aircraft noise source(s). The microphone shall be positioned five feet above the ground.
(C) Analysis of data. The interior and exterior sound level shall be recorded for each aircraft noise event. The difference in level between the exterior and interior sound level shall also be recorded on the data sheet submitted to the building official. At least 100 events shall be measured. The events should be reasonably representative of the various aircraft types which operate at the MCAS and airport. The energy averaged value of the difference in level measured shall be calculated and reported as the noise level reduction (NLR).
(D) Documentation. The report of, findings shall include the following:
(1) Hard copy of instrument printouts of all measurements.
(2) Tabulation of the single event sound levels, sound level differences and calculation of energy averaged value of the sound level differences.
(3) Evidence of calibration of equipment before and after test.
(4) A certification that the measurements are true and accurate.
('80 Code, § 7-50) (Ord. 1857, passed 7-18-79)