BACKGROUND AND PURPOSE: Low-frequency tones (LFT) and infrasound (IS) are looked upon as potentially hazardous to human health. We aimed at assessing LFT/IS-induced activation of the auditory cortex by using fMRI. MATERIALS AND METHODS: fMRI was used to investigate LFT/IS perception in 17 healthy volunteers. Short tone bursts of 12, 36, 48 and 500 Hz were delivered directly into the right external ear canal through a 12-m long silicone tube and an ear plug. Sound pressure levels (SPL) and spectral analysis of the stimuli and scanner noise were measured in situ by using a metal-free optical microphone and a fiber-optic cable. RESULTS: SPL-dependent activation of the superior temporal gyrus, i.e. Brodmann areas (BA) 41 and 42 as well as BA 22, was delineated subsequent to acoustic stimulation with 12-, 48- and 500-Hz stimuli. Thresholds for LFT/IS-induced brain activation were between 110 and 90 dB SPL in normal hearing subjects. Spectral analysis revealed the occurrence of harmonics together with LFT, of which 36-Hz harmonics interfered with IS exposure at 12 Hz as well as scanner noise. CONCLUSION: Our results provide evidence that auditory cortex activation may be induced by LFT/IS exposure, depending on sound pressure levels applied. Clinical implications of our findings will have to be addressed by subsequent studies involving patients presumptively suffering from LFT-dependent disorders.
BACKGROUND AND PURPOSE: Low-frequency tones (LFT) and infrasound (IS) are looked upon as potentially hazardous to human health. We aimed at assessing LFT/IS-induced activation of the auditory cortex by using fMRI. MATERIALS AND METHODS: fMRI was used to investigate LFT/IS perception in 17 healthy volunteers. Short tone bursts of 12, 36, 48 and 500 Hz were delivered directly into the right external ear canal through a 12-m long silicone tube and an ear plug. Sound pressure levels (SPL) and spectral analysis of the stimuli and scanner noise were measured in situ by using a metal-free optical microphone and a fiber-optic cable. RESULTS: SPL-dependent activation of the superior temporal gyrus, i.e. Brodmann areas (BA) 41 and 42 as well as BA 22, was delineated subsequent to acoustic stimulation with 12-, 48- and 500-Hz stimuli. Thresholds for LFT/IS-induced brain activation were between 110 and 90 dB SPL in normal hearing subjects. Spectral analysis revealed the occurrence of harmonics together with LFT, of which 36-Hz harmonics interfered with IS exposure at 12 Hz as well as scanner noise. CONCLUSION: Our results provide evidence that auditory cortex activation may be induced by LFT/IS exposure, depending on sound pressure levels applied. Clinical implications of our findings will have to be addressed by subsequent studies involving patients presumptively suffering from LFT-dependent disorders.
Authors: Markus Weichenberger; Martin Bauer; Robert Kühler; Johannes Hensel; Caroline Garcia Forlim; Albrecht Ihlenfeld; Bernd Ittermann; Jürgen Gallinat; Christian Koch; Simone Kühn Journal: PLoS One Date: 2017-04-12 Impact factor: 3.240
Authors: Robert G Berger; Payam Ashtiani; Christopher A Ollson; Melissa Whitfield Aslund; Lindsay C McCallum; Geoff Leventhall; Loren D Knopper Journal: Front Public Health Date: 2015-02-24
Authors: Rory J Lubner; Neil S Kondamuri; Renata M Knoll; Bryan K Ward; Philip D Littlefield; Derek Rodgers; Kalil G Abdullah; Aaron K Remenschneider; Elliott D Kozin Journal: Front Neurol Date: 2020-04-28 Impact factor: 4.003