Abstract
Magnetoencephalography (MEG) is a non-invasive technique for 3D brain imaging. This imaging system measures extremely weak magnetic fields emerging from the head that are associated with brain electrical activity. Cortical brain responses to sound can be measured using MEG to detect these magnetic fields. Sound is piped to the subject's ears while observing the magnetic activity surrounding the brain. The sound system used must not produce magnetic fields which interfere with the MEG sensors. For this reason the transducers are located outside the MEG sensor room and pneumatic tubes are used to deliver sound to the subject. The tubes are made of a non-magnetic material and can be up to four metres in length. The use of long pneumatic tubes leads to some loss of high frequency components in the audio signal. The type of transducer chosen to drive the tubes will also affect high frequency signal content. When the sound has a deficit in the high frequency range, it is perceived to be muffled and speech intelligibly suffers. Speech stimuli such as fricatives that contain high frequency content become degraded and the range of useful speech stimuli tests for auditory brain function assessment using MEG becomes restricted. The Speech Intelligibility Standard set out by ANSI requires a minimum high frequency response of 8000 Hz for 100% intelligibility. The frequency response of a new audio system that was developed extends to 9000 Hz. This system is compared with an existing commercial sound system for MEG with a high frequency roll-off occurring at 2000 Hz. Copyright
| Original language | English |
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| Title of host publication | 20th International Congress on Acoustics 2010, ICA 2010 - Incorporating Proceedings of the 2010 Annual Conference of the Australian Acoustical Society |
| Place of Publication | Sydney |
| Publisher | International Congress on Acoustics (ICA) |
| Pages | 1018-1022 |
| Number of pages | 5 |
| Volume | 2 |
| ISBN (Print) | 9781617827457 |
| Publication status | Published - 2010 |
| Event | 20th International Congress on Acoustics 2010, ICA 2010 - Incorporating the 2010 Annual Conference of the Australian Acoustical Society - Sydney, NSW, Australia Duration: 23 Aug 2010 → 27 Aug 2010 |
Other
| Other | 20th International Congress on Acoustics 2010, ICA 2010 - Incorporating the 2010 Annual Conference of the Australian Acoustical Society |
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| Country/Territory | Australia |
| City | Sydney, NSW |
| Period | 23/08/10 → 27/08/10 |