{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,30]],"date-time":"2026-09-30T18:35:19Z","timestamp":1790793319616,"version":"4.1.0"},"reference-count":53,"publisher":"Acoustical Society of America (ASA)","issue":"1","content-domain":{"domain":["pubs.aip.org"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2001,1,1]]},"abstract":"<jats:p>Approaches were examined for reducing acoustic noise levels heard by subjects during functional magnetic resonance imaging (fMRI), a technique for localizing brain activation in humans. Specifically, it was examined whether a device for isolating the head and ear canal from sound (a \u201chelmet\u201d) could add to the isolation provided by conventional hearing protection devices (i.e., earmuffs and earplugs). Both subjective attenuation (the difference in hearing threshold with versus without isolation devices in place) and objective attenuation (difference in ear-canal sound pressure) were measured. In the frequency range of the most intense fMRI noise (1\u20131.4 kHz), a helmet, earmuffs, and earplugs used together attenuated perceived sound by 55\u201363 dB, whereas the attenuation provided by the conventional devices alone was substantially less: 30\u201337 dB for earmuffs, 25\u201328 dB for earplugs, and 39\u201341 dB for earmuffs and earplugs used together. The data enabled the clarification of the relative importance of ear canal, head, and body conduction routes to the cochlea under different conditions: At low frequencies (\u2a7d500 Hz), the ear canal was the dominant route of sound conduction to the cochlea for all of the device combinations considered. At higher frequencies (&amp;gt;500 Hz), the ear canal was the dominant route when either earmuffs or earplugs were worn. However, the dominant route of sound conduction was through the head when both earmuffs and earplugs were worn, through both ear canal and body when a helmet and earmuffs were worn, and through the body when a helmet, earmuffs, and earplugs were worn. It is estimated that a helmet, earmuffs, and earplugs together will reduce the most intense fMRI noise levels experienced by a subject to 60\u201365 dB SPL. Even greater reductions in noise should be achievable by isolating the body from the surrounding noise field.<\/jats:p>","DOI":"10.1121\/1.1326083","type":"journal-article","created":{"date-parts":[[2002,7,26]],"date-time":"2002-07-26T14:21:16Z","timestamp":1027693276000},"page":"216-231","update-policy":"https:\/\/doi.org\/10.1063\/aip-crossmark-policy-page","source":"Crossref","is-referenced-by-count":86,"title":["Isolating the auditory system from acoustic noise during functional magnetic resonance imaging: Examination of noise conduction through the ear canal, head, and body"],"prefix":"10.1121","volume":"109","author":[{"given":"Michael E.","family":"Ravicz","sequence":"first","affiliation":[{"name":"Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, Massachusetts\u200902114"},{"name":"Research Laboratory of Electronics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts\u200902139"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jennifer R.","family":"Melcher","sequence":"additional","affiliation":[{"name":"Eaton-Peabody Laboratory, Boston, Massachusetts\u200902114"},{"name":"Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts\u200902115"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"231","reference":[{"key":"2023071400011731100_ans"},{"key":"2023071400011731100_ban","doi-asserted-by":"crossref","first-page":"410","DOI":"10.1002\/mrm.1910390311","article-title":"Functional MRI of brain activation induced by scanner acoustic noise","volume":"39","year":"1998","journal-title":"Magn. 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