A comprehensive experimental study of micro-perforated panel acoustic absorbers in MRI scanners

A comprehensive experimental study has been conducted to investigate the possibilities of using micro-perforated panel (MPP) acoustic absorbers in magnetic resonance imaging (MRI) scanners. The experimental acoustic measurements include measurements in an impedance tube, measurements in an MRI scanner bore mock-up, and in situ measurements in an actual MRI scanner. The experimental results are in good agreement with theoretical calculations. This study confirms that MPP acoustic absorbers have multiple absorption frequency bands and wider frequency bands at higher frequency ranges when they are used in cylindrically shaped ducts such as MRI scanner bores. It has also been found that the acoustic noise level in the scanner bore is significantly increased when the air gap depth behind the MPP is too large. This study shows that an MPP absorber, when properly designed, is effective in reducing the acoustic noise in MRI scanners. And, when designing an MPP absorber for MRI scanners, the air gap depth should be carefully considered.