Does airborne ultrasound lead to activation of the auditory cortex?

TY - JOUR

T1 - Does airborne ultrasound lead to activation of the auditory cortex?

AU - Kühler, Robert

AU - Weichenberger, Markus

AU - Bauer, Martin

AU - Hensel, Johannes

AU - Brühl, Rüdiger

AU - Ihlenfeld, Albrecht

AU - Ittermann, Bernd

AU - Sander, Tilmann

AU - Kühn, Simone

AU - Koch, Christian

PY - 2019/8/27

Y1 - 2019/8/27

N2 - As airborne ultrasound can be found in many technical applications and everyday situations, the question as to whether sounds at these frequencies can be heard by human beings or whether they present a risk to their hearing system is of great practical relevance. To objectively study these issues, the monaural hearing threshold in the frequency range from 14 to 24 kHz was determined for 26 test subjects between 19 and 33 years of age using pure tone audiometry. The hearing threshold values increased strongly with increasing frequency up to around 21 kHz, followed by a range with a smaller slope toward 24 kHz. The number of subjects who could respond positively to the threshold measurements decreased dramatically above 21 kHz. Brain activation was then measured by means of magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) and with acoustic stimuli at the same frequencies, with sound pressure levels (SPLs) above and below the individual threshold. No auditory cortex activation was found for levels below the threshold. Although test subjects reported audible sounds above the threshold, no brain activity was identified in the above-threshold case under current experimental conditions except at the highest sensation level, which was presented at the lowest test frequency.

AB - As airborne ultrasound can be found in many technical applications and everyday situations, the question as to whether sounds at these frequencies can be heard by human beings or whether they present a risk to their hearing system is of great practical relevance. To objectively study these issues, the monaural hearing threshold in the frequency range from 14 to 24 kHz was determined for 26 test subjects between 19 and 33 years of age using pure tone audiometry. The hearing threshold values increased strongly with increasing frequency up to around 21 kHz, followed by a range with a smaller slope toward 24 kHz. The number of subjects who could respond positively to the threshold measurements decreased dramatically above 21 kHz. Brain activation was then measured by means of magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) and with acoustic stimuli at the same frequencies, with sound pressure levels (SPLs) above and below the individual threshold. No auditory cortex activation was found for levels below the threshold. Although test subjects reported audible sounds above the threshold, no brain activity was identified in the above-threshold case under current experimental conditions except at the highest sensation level, which was presented at the lowest test frequency.

KW - Journal Article

U2 - 10.1515/bmt-2018-0048

DO - 10.1515/bmt-2018-0048

M3 - SCORING: Journal article

C2 - 30657739

VL - 64

SP - 481

EP - 493

JO - BIOMED ENG-BIOMED TE

JF - BIOMED ENG-BIOMED TE

SN - 0013-5585

IS - 4

ER -