Active reduction of high-level acoustic noise on a fMRI test-bed using labview and FPGA platforms

We present an Active Noise Control (ANC) system that is designed to cancel acoustic noise at high sound levels. The ANC system is graphically designed using Lab VIEW and implemented on FPGA. NLMS algorithm is used for updating the filter co-efficients. The ANC system is evaluated on a realistic test-bed mimicking an actual fMRI bore. The algorithm is tested for various tonal frequencies in the range from 100 to 5000 Hz and the performance is measured in terms of the noise cancellation. We observe that good noise cancellation (15 to 45 dB SPL) can be obtained with NLMS algorithm over the entire bandwidth.