Active noise control of magnetic resonance imaging scanner using inverse modeling technique.

Abstract

In active noise control applications, internal model control (IMC) is a strategy to convert from feedback to feedforward control. In this configuration, the optimal solution of the controller will be the inverse model of the secondary path. However, the inverse model of the secondary path may not always exist. In fact, for the non‐minimal phase system, the inverse model is unstable. In this case, the non‐causal or delayed version of the inverse model will be employed. In general, this approach is not suitable for active noise control if the objective is to treat broadband noise. However, for harmonic signal control, this is not an issue. Magnetic resonance imaging (MRI), a procedure for medical diagnosis and biomedical research, generates undesirable levels of acoustic noise emission. The noise is normally dominated by clusters of harmonics throughout the audio spectrum. Due to its tonal nature, MRI noise control is a candidate for IMC. In this paper, an active noise control scheme using the inverse modeling technique is proposed and studied for pre‐recorded MRI noises obtained during operation of a 4T whole‐body MRI scanner. The recorded MRI noise is played back through a stereo system in a sound quality room and controlled using a headset equipped with the proposed active controller. The results demonstrate almost 20 dB reduction can be achieved.