Frequencies of inaudible high-frequency sounds differentially affect brain activity: positive and negative hypersonic effects

The hypersonic effect is a phenomenon in which sounds containing significant quantities of non-stationary high-frequency components (HFCs) above the human audible range (max. 20 kHz) activate the midbrain and diencephalon and evoke various physiological, psychological and behavioral responses. Yet i...

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Bibliographic Details
Published in:PloS one 2014-04, Vol.9 (4), p.e95464
Main Authors: Fukushima, Ariko, Yagi, Reiko, Kawai, Norie, Honda, Manabu, Nishina, Emi, Oohashi, Tsutomu
Format: Article
Language:English
Subjects:
Acoustics
Biology and Life Sciences
Brain
Brain - physiology
Brain research
Diencephalon
Echo sounding
EEG
Electroencephalography
Emergence
Engineering and Technology
Experiments
Gamelan music
Humans
Hydrofluorocarbons
Medicine and Health Sciences
Mesencephalon
Neurosciences
Noise
Psychological aspects
R&D
Research & development
Research and Analysis Methods
Social Sciences
Sound
Studies
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Summary:The hypersonic effect is a phenomenon in which sounds containing significant quantities of non-stationary high-frequency components (HFCs) above the human audible range (max. 20 kHz) activate the midbrain and diencephalon and evoke various physiological, psychological and behavioral responses. Yet important issues remain unverified, especially the relationship existing between the frequency of HFCs and the emergence of the hypersonic effect. In this study, to investigate the relationship between the hypersonic effect and HFC frequencies, we divided an HFC (above 16 kHz) of recorded gamelan music into 12 band components and applied them to subjects along with an audible component (below 16 kHz) to observe changes in the alpha2 frequency component (10-13 Hz) of spontaneous EEGs measured from centro-parieto-occipital regions (Alpha-2 EEG), which we previously reported as an index of the hypersonic effect. Our results showed reciprocal directional changes in Alpha-2 EEGs depending on the frequency of the HFCs presented with audible low-frequency component (LFC). When an HFC above approximately 32 kHz was applied, Alpha-2 EEG increased significantly compared to when only audible sound was applied (positive hypersonic effect), while, when an HFC below approximately 32 kHz was applied, the Alpha-2 EEG decreased (negative hypersonic effect). These findings suggest that the emergence of the hypersonic effect depends on the frequencies of inaudible HFC.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0095464