  The high-intensity, repetitive noise associated with functional magnetic
resonance imaging hinders on-line monitoring of subjects' speech and/or
recording speech signals suitable for off-line analysis. The proposed algorithm
enhances the speech signal by suppressing the scanner noise in the signal
recorded by a single-channel microphone. Significant increases in
signal-to-noise ratio are achieved using an adaptive filter that combines time
and frequency domain elements. In addition to providing a recording suitable
for speech analysis, such a real-time system provides an alternative means (to,
e.g., the "panic ball") for communication between the patient and the operator
during image acquisition.
