PhonicTrap DuctingPhonicTrap Ducting With its superior acoustic capabilities, PhonicTrapTM ducting effectively reduces airflow noise in your ventilation system. PhonicTrapTM ducting contains three layers for reducing noise without impacting airflow. The inner lining is perforated to allow air to flow between this layer and the central layer. This design reduces the creation of back pressure on the fan. The central layer is woven non allergenic polyester wadding, which