Active control of the volume acquisition noise in functional magnetic resonance imaging: Method and psychoacoustical evaluation
Active control of the volume acquisition noise in functional magnetic resonance imaging: Method and psychoacoustical evaluation
复制标题
DOI：
10.1121/1.1408948
复制
发表时间：
2001-12-01
影响因子：
2.4
通讯作者：
Palmer, AR
中科院分区：
文献类型：
--
作者：
Chambers, J;Akeroyd, MA;Palmer, AR
功能磁共振成像(FMRI)提供了一种非侵入性的工具，可以在受试者听声音时观察大脑中神经活动的相关性。然而，在获取MR图像的过程中会产生强烈的噪声。这种噪音刺激听觉神经系统，限制了可用于显示刺激驱动活动的动态范围。噪音可能会损害听力，并会分散受试者的注意力。在有源噪声控制(ANC)系统中，噪声的参考样本被处理以形成与听者耳朵处的噪声破坏性地相加的声音。我们描述了一种在电磁恶劣和物理紧凑的MRI扫描环境中实现ANC的方法。首先，在实验室中对一个原型系统进行了心理声学评估，以产生噪声的扬声器的电驱动为参考。该系统在250赫兹至1千赫频率范围内主观降噪10-20分贝，在较高频率时降噪效果较小。该系统被修改为在真实的MR扫描仪中操作，其中通过记录声学扫描仪的噪声来获得参考。在500~3500 Hz的频率范围内，扫描仪噪声中最强分量的客观降幅为30~40d B，在600 Hz和1.9 kHz的测试中，主观降幅分别为12 d B和5 d B。尽管ANC的益处受到耳道的空气传导途径以外的传输路径的限制，但ANC即使在最大骨传导的频率范围(1.5-2 kHz)也能获得有价值的衰减。因此，ANC在听觉功能磁共振成像中应该是普遍有用的。(C)2001年美国声学学会。
Functional magnetic resonance imaging (fMRI) provides a noninvasive tool for observing correlates of neural activity in the brain while a subject listens to sound. However, intense acoustic noise is generated in the process of capturing MR images. This noise stimulates the auditory nervous system, limiting the dynamic range available for displaying stimulus-driven activity. The noise is potentially damaging to hearing and is distracting for the subject. In an active noise control (ANC) system, a reference sample of a noise is processed to form a sound which adds destructively with the noise at the listener's ear. We describe an implementation of ANC in the electromagnetically hostile and physically compact MRI scanning environment. First, a prototype system was evaluated psychoacoustically in the laboratory, using the electrical drive to a noise-generating loudspeaker as the reference. This system produced 10-20 dB of subjective noise-reduction between 250 Hz and 1 kHz, and smaller amounts at higher frequencies. The system was modified to operate in a real MR scanner where the reference was obtained by recording the acoustic scanner noise. Objective reduction by 30-40 dB of the most intense component in scanner noises was realized between 500 Hz and 3500 Hz, and subjective reduction of 12 dB and 5 dB in tests at frequencies of 600 Hz and at 1.9 kHz, respectively. Although the benefit of ANC is limited by transmission paths to the cochlea other than air-conduction routes from the auditory meatus, ANC achieves worthwhile attenuation even in the frequency range of maximum bone conduction (1.5-2 kHz). ANC should, therefore, be generally useful during auditory fMRI. (C) 2001 Acoustical Society of America.