The following publications are directly linked to the projects EMRP HLT01 Ears and EMPIR 15HLT03 Ears II:

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Investigation of hearing perception at ultrasound frequencies by functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG)

Author(s): Robert Kühler, Markus Weichenberger, Martin Bauer, Simone Kühn, Tilmann Sander-Thömmes, Albrecht Ihlenfeld, Bernd Ittermann, Johannes Hensel and Christian Koch
Journal: PROCEEDINGS of the 22nd International Congress on Acoustics
Year: 2016
Month: September
Abstract: Airborne ultrasound is applied in many technical and medical processes and has increasingly moved into daily life. Because of a potential exposure of humans the question whether sound at these frequencies can be heard and whether these sounds can be of any risk for the hearing system or for wellbeing and health of an individual in general, is of great practical relevance. To study these issues audiological methods and neuroimaging were combined in order to obtain an objective rationale of the auditory perception of airborne ultrasound in humans. In a first step the monaural pure-tone hearing threshold for 26 young test subjects (19 – 33 years) in the frequency range from 14 to 24 kHz was determined. The hearing threshold values rose steeply with increasing frequency up to around 21 kHz followed by a range with smaller slope towards 24 kHz. In a next step neuroimaging techniques were applied to find brain activation following the stimulation by ultrasound between 20 and 24 kHz. Functional magnetic resonance imaging (fMRI) with sound pressure levels slightly above and below individual threshold was used in experiments with the same test persons as in the audiological measurements. Although test subjects reported audible sensation no brain activation could be identified in the above-threshold case except for the lowest test frequency at 14 kHz. Magnetoencephalography (MEG) was employed as an alternative method with the same test person group. Brain activation was measured, but again no auditory cortex activation was found above 14 kHz.

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