Low mass high transmission loss portable quiet room for very important personnel protection

摘要

This case study analyzes the design, construction and testing of a lightweight, easilytransportable speech isolation room capable of providing substantial anti-eavesdroppingcounter measures for use by high level government and intelligence agencies as a securemeeting and communications center that can be readily deployed worldwide. Theperformance criteria specifying a minimum field STC-35 utilizing a modular, scalablemechanical design capable of repeated assembly without the use of tools, a maximum totaldesign weight of 3.29 lbs per square foot, a 2” nominal wall thickness and the incorporationof active and passive ventilation dictated the development of a robust, multi-layeredcomposite panel and joining system as well as ancillary components. Using a combinationof non-metallic limp mass and rigid metallic barriers separated by decouplers of varyingproperties in an aluminum shell brake-formed to distort natural resonance, we were able toachieve significant TL (up to 45 dB) in the speech range of frequencies equaling theperformance of commercially available products of nearly twice the weight and bulk.Interior room acoustical characteristics were optimized by using modular demountablesound absorptive units.