Active Cancellation of Dive Helmet Communication System Noise

In this project we propose to demonstrate the potential of active noise control to reduce acoustic noise in Navy dive helmets by up to 15dB. Emphasis will be placed on reducing noise caused by breathing apparatus and communication system noise and on developing a complementary high fidelity simulation model. The measured signals will be used in a simulation of the ANC system to indicate the achievable active attenuation at the divers ears and the potential of ANC for diving helmet noise reduction. The base and option tasks include: 1) Simulation model and control of breathing apparatus noise, 2) Control of communication channel feedback loop noise, 3) Finite Element model of dive helmet acoustic dynamics, and 4) Investigate optimal ANC component locations.In Phase I, a premier team with extensive expertise in active noise control, testing, Finite Element modeling and master diving will instrument and measure exterior and interior noise signals in a dive helmet during underwater high noise operating conditions. The data will be processed and used to develop an simulation model of the ANC system. The model will be exercised to optimize the ANC system for maximum noise reduction in the helmet. Finite Element models will be created and used for preliminary investigations of the acoustic dynamics of the dive helmet interior. Optional tasks include developing a simulation model of in wire ANC of background noise on diver communications.