Optimal Design of Active Noise Control Systems

In Phase I, Vibro-Acoustic Sciences will extend its proprietary Statistical Energy Analysis (SEA) code to estimate the statistics of phase for single input - single output transfer functions between launch vehicle fairing and payload acoustic volume. Thisis an extension of the preliminary research for AFRL on the same topic, conducted in 2000 by Vibro-Acoustic Science's collaborator and subcontratcor Prof. C.R Fuller of Virginia Tech. The statistcal phase prediction method will be experimentally validatedwith a simple laboratory experiment. The method will then be incorporated in Vibro-Acoustic Sciences' fairing active noise control model (developed in part under Air Force SBIR AF00-041) to theroretically predict how much active noise noise reduction ispossible inside a fairing when the external acoustic excitation is partially space-correlated (ie. multiple statistcally independent sources) and when the internal payload acoustic field is reverberant.The method and experimental results developed in thefirst two phases of the SBIR program will be applicable to DoD and commercial launch vehicles and can be intergrated into the commercial software products already provided to these markets by Vibro-Acoustic Sciences. The successful application of thedesign method will reduce launch vehicle fairing acoustic levels and allow the use of more low cost COTS equipment on space vehicles.