Active Noise Control System for Reducing MR Noise

Masafumi KUMAMOTO  Masahiro KIDA  Ryotaro HIRAYAMA  Yoshinobu KAJIKAWA  Toru TANI  Yoshimasa KURUMI  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E94-A   No.7   pp.1479-1486
Publication Date: 2011/07/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E94.A.1479
Print ISSN: 0916-8508
Type of Manuscript: PAPER
Category: Engineering Acoustics
active noise control,  magnetic resonance imaging device,  optical microphone,  piezoelectric loudspeaker,  digital signal processor,  

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We propose an active noise control (ANC) system for reducing periodic noise generated in a high magnetic field such as noise generated from magnetic resonance imaging (MRI) devices (MR noise). The proposed ANC system utilizes optical microphones and piezoelectric loudspeakers, because specific acoustic equipment is required to overcome the high-field problem, and consists of a head-mounted structure to control noise near the user's ears and to compensate for the low output of the piezoelectric loudspeaker. Moreover, internal model control (IMC)-based feedback ANC is employed because the MR noise includes some periodic components and is predictable. Our experimental results demonstrate that the proposed ANC system (head-mounted structure) can significantly reduce MR noise by approximately 30 dB in a high field in an actual MRI room even if the imaging mode changes frequently.