System Set-Up And Calibration - Cambridge Sound Management Qt Emitters Installation And Operation Manual

SYST E M SE T- UP AND CALIBR ATIO N

System Set-Up And Calibration

Acoustic calibration
Direct Field technology minimizes the need for equalization or measurements during system setup.
Sensitivity and efficiency of the emitter array is known and listeners are typically in the direct field of
emitters without an intervening acoustical ceiling which would change the effective output level and
frequency response of the system. In most cases the room acoustics of offices have minimal effect
on either. Therefore it is possible to preset system equalization at the factory and make volume level
control settings by the installer dependent only on user and project requirements.
If a calibrated sound level meter or CSM's iPad app with a Studio Six calibrated microphone is available
we suggest setting level controls initially for a space averaged level of approximately 45 - 48 dBA.
However, it is also recommended that the masking level reduced until listeners in the spaces adjacent
the protected room are unable to understand any speech originating in the room from a male and a
female talker speaking with raised voice. Speech intelligibility should be checked by a listener with
good hearing all along the party wall, within a few inches, and in any areas beyond the emitter coverage
area. Once that level is determined a 3 dBA increase in masking level is recommended as an operating
safety margin. It is not possible to specify an operating level in advance as the sound isolation of the
room construction has an important effect on the speech privacy and cannot be known accurately
in advance. Even though the laboratory ratings of sound transmission class (STC) for the various
components may be known, the actual performance in the field (Field STC) typically varies greatly due
to the construction practices employed. The goal is to set the masking level as low as possible while
still achieving Confidential privacy throughout the spaces adjacent to the protected room. This will
minimize annoyance to office staff outside the protected room.
If using iPad app, set levels directly below first row of emitters.
A similar setup procedure without a calibrated meter is also possible.
Ceiling Height
8' (2.4 meters)
10' (3 meters)
12' (3.6 meters)
Qt Conference Room Edition Installation and Operations Guide
Volume Level
13 - 16
15 - 18
16 - 19
Intended Result (at listener ear level)
45 - 48 dBA
45 - 48 dBA
45 - 48 dBA
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