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An Active Noise Cancellation System for fMRI

MRI acoustic noise could be high up to 120 dB while acquiring images with high speed echo planar imaging (EPI). It reaches the hearing limit of human and also impedes the research of functional MRI. In this research, an active noise cancellation (ANC) system was implemented using a filtered-x recursive least-square (FXRLS) filter and combined with passive noise cancellation to reduce the noise from EPI. Further, the visual fMRI experiments were performed with and without the ANC system. Our results showed extra 9.4 dB reduction was obtained by active noise cancellation at the main frequency of EPI noise. Besides, the fMRI results showed 140% activated pixel numbers increased.