Noise analysis and active noise control strategy of transcranial magnetic stimulation device

Transcranial magnetic stimulation (TMS) has been proved to be effective in the treatment of many psychiatric disorders, but the clicking noise produced by the large and short pulse current in the TMS coil may put negative effect to the hearing of patients. However, current researches on noise control of the TMS device are very limited. In this paper, by analyzing the actual noise signal of TMS, the mechanism of noise generation of the device is explained. According to the therapeutic schedule of TMS, an active noise control (ANC) strategy for TMS device with online identification, offline analysis, and real-time output is proposed. A finite element analysis model of noise propagation and noise control of the device is established. The strategy steps are as follows: the secondary pathway is constructed at first; during the first stimulation sequence, the coil noise received by the human ear is collected in real-time, and the noise is analyzed offline; the secondary signal is then produced to reduce the following noise in real-time. The simulation results show that the proposed ANC strategy for TMS can effectively reduce the noise with certain robustness.