Silencers can reduce noise produced by air turbulence in a fan. However, only the airstream that passes through the silencer sees a noise reduction. Breakout noise through the fan housing and breakout noise through ductwork or flex connectors before the silencer will not see a reduction in noise. Vibration noise and mechanical noise generated by the motor and drive will also not be reduced by a silencer. Sound insulation or sound enclosures may be necessary to reduce noise levels that are outside the influence of a silencer.
IATC fan sound ratings are estimated for (8) octave bands. Our sound data is estimated using generalized conditions for field, directivity, airflow and silencer termination, including distance and angle relative to the listener. Prudent design techniques would dictate that these default values be reviewed by the customer since many calculations are dependent on specific site conditions.
Customer specifications asking for specific fan sound levels are difficult if not impossible to guarantee. Site conditions, adjacent reflecting surfaces, other sources of noise, all make it extremely difficult to predict final noise outcomes. If this level of assurance is required, we recommend our customers consult with a qualified acoustical sound engineer that can evaluate all system factors.