Design and Construction Handbook - Los Angeles World Airports

Guide Specification
5. Total Harmonic Distortion: Maintain previous setup. Measure at reference operating
level at 63 Hz, 125 Hz, 1 kHz, 10 kHz.
G. Electro/Acoustic Tests:
1. Uniformity of coverage.
2. Electronic and acoustic frequency response/one third octave equalization. Measure at ear
level. Comply with applicable portions of ANSI (SMPTE) PH22.202M-1984, "B chain
electro-acoustic response - control rooms and indoor theaters." Adjust to "curve X of B
chain characteristic". Representative of the Owner will direct final adjustment.
3. Maximum continuous sound pressure level (in the reverberant field). Drive systems with
broadband pink noise. Sustain for at least five minutes with no system damage. Measure
for "A" and "C" weightings at ear level on loudspeaker axis. Turn off noise.
4. Acoustic signal to noise ratio referenced to the specified maximum continuous sound
pressure level in the reverberant field. Measure for "A" and "C" weightings at ear level
on loudspeaker axis with mechanical systems operating. Present comparison with
previous measurement.
5. Acoustic gain before feedback. Locate acoustic source (4 inch loudspeaker/pink noise
generator) two feet from system microphone. Measure at system microphone position
and at most distant listener position at ear level. Present comparison.
H. System Overall:
1. Verify levels.
2. Provide permanent "wedge" type labels on all controls, as applies, to indicate correct
settings after systems performance testing and adjustment procedures have been
successfully completed.
I. At least 10% of the total number of zones must be tested at two different times and at two
different locations within the zone during peak hours and during quiet hours. These tests must
indicate that pages are at least 6dB, but no greater than 10dB above, ambient noise levels.
Measured ambient noise levels must be time averaged over a period of at least one minute and
are not to include announcements from the paging system.
J. Upon completion of the installation of all loudspeakers in an area, perform the following tests
and record results. Correct non-conforming conditions, unless the cause is clearly outside the
Work of this Section, in which case submit the apparent cause to the Owner.
1. Loudspeaker Line Impedance: At terminal cabinets at equipment rooms, measure the
impedance of each loudspeaker line. Sweep from at least 20 Hz to at least 16 kHz.
2. Loudspeaker Polarity: Test the acoustic polarity of all loudspeakers using an Acoustic
Polarity Tester.
PAGING SYSTEMS
27 51 13 - 32
Communication Systems