Simulation of acoustical noise reduction for magnetic resonance imaging by an active control headphone with piezoelectric plate and earmuff

Magnetic resonance imaging (MRI) machines are widely used for medical examinations. However, they generate acoustical noise with sound pressure levels exceeding 100 dB. To solve this problem, we propose a headphone that uses active noise control (ANC) by a piezoelectric vibration plate in combination with an earmuff. This paper presents the results of analyzing MRI noise and shows the simulated noise reduction performance for the headphones with an inverse filter for pre-whitening in the simulated MRI room. Because MRI examination rooms are high-magnetic-field environments, all magnetic materials are prohibited. The proposed headphone uses a piezoelectric vibration plate made from a nonmagnetic material. Feedforward control is employed because the MRI noise has a pulse waveform with unstable amplitude. The headphone showed good noise reduction performance in the low-frequency band by ANC and in the high-frequency band by earmuff. The noise level was reduced to 67.9 dB. The headphone provides a more comfortable acoustic environment than the earmuff alone for a subject undergoing an MRI examination.