Functional Magnetic Resonance Imaging Study of Phonetic Identification.
Grant-in-Aid for Scientific Research (C)
|Allocation Type||Single-year Grants|
|Research Institution||The University of Tokyo|
SEKIMOTO Sotaro The University of Tokyo, Graduate School of Medicine, Associate, 大学院・医学系研究科, 助手 (00010059)
|Project Period (FY)
1998 – 1999
Completed(Fiscal Year 1999)
|Budget Amount *help
¥3,300,000 (Direct Cost : ¥3,300,000)
Fiscal Year 1999 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1998 : ¥2,500,000 (Direct Cost : ¥2,500,000)
|Keywords||functional MRI / fMRI / Active Noise Control / ANC / 音韻知覚|
1. FMRI Activation Study for Phoneme Judgement.
The cortical fMRI response was measured when subjects identified whether phoneme [nu] was included in Japanese nonsense two-syllable stimuli. The activation was observed on the left and right superior temporal gyri with left hemisphere dominance.
2. Development of Speech Stimulus Presentation Method under fMRI Sound Noise Environment.
For the speech hearing research, the use of the fMRI is restricted by undesired acoustic noise generated by the gradient system. The loud noise disturbs the hearing of speech stimulus. Therefore, sound protection is significant for the fMRI study in speech perception research. Typical sound protection material cannot be used because of the effect of magnetic field generated by MRI equipment. In the present study, the active noise cancellation method (ANC) was used to reduce the MRI sound noise in ears combined with the traditional passive sound proof technique, because ANC is especially effective in low frequency whereas passive technique is effective in high frequency. The following items were studied :
(1) The measurement of acoustic properties of the sound noise.
(2) The measurement of the timing relationships between the sound noise waveform and gradient pulse waveforms.
(3) Development of the active noise cancellation system.
(4) Development of the non-magnetic transducer for ANC control.
The peak level of the sound noise was reduced by 15 dB using ANC method. The overall reduction of sound noise was more than 40 dB when ANC was combined with the traditional passive soundproof technique. As a result, the speech perception research using fMRI became available under the high intensity sound noise.
Research Output (15results)