Authors: 
Ryuma Kuribayashi, Ryuta Yamamoto, & Hiroshi Nittono

Title:
High-resolution music with inaudible high-frequency components produces a lagged
 effect on human electroencephalographic activities

Journal:
NeuroReport, 25(9), 657ー661. 

doi:
10.1097/WNR.000000000000015

論文URL (DOIが間違ってリンクされているので PubMed からどうぞ）:
http://www.ncbi.nlm.nih.gov/pubmed/24722228

Abstract:
High-quality digital sound sources with inaudible high-frequency components 
(above 20 kHz) have become available because of recent advances in information 
technology. Listening to such sounds has been shown to increase the [alpha]-band
 power of an electroencephalogram (EEG). The present study scrutinized the time 
course of this effect by recording EEG along with autonomic measures (skin 
conductance level and heart rate) and facial electromyograms (corrugator 
supercilii and zygomaticus major). Twenty university students (19-24 years old) 
listened to two types of a 200-s musical excerpt (J. S. Bach’s French Suite No. 
5) with or without inaudible high-frequency components using a double-blind 
method. They were asked to rate the sound quality and to judge which excerpt 
contained high-frequency components. High-alpha EEG power (10.5-13 Hz) was 
larger for the excerpt with high-frequency components than for the excerpt 
without them. This effect was statistically significant only in the last quarter
 of the period (150-200 s). Participants were not able to distinguish between 
the excerpts, which did not produce any discernible differences in subjective, 
autonomic, and facial muscle measures. This study shows that inaudible high-
frequency components have an impact on human brain activity without conscious 
awareness. Unlike a standard test for sound quality, at least 150 s of exposure 
is required to examine this effect in future research.

著者Contact先の email:
nittono@hiroshima-u.ac.jp

日本語によるコメント
「耳には聞こえない2万ヘルツ以上の音を含むディジタル音源を聴いているときは，同じ
音源で高周波帯域をカットしたものを聴いているときに比べて，意識的には違いが分から
ないのに，高周波アルファ帯域の脳波パワーが増大する」という研究です。ハイパーソニ
ック（hypersonic）効果として20年以上前から知られている現象ですが，今回は二重盲検
法で追試し，効果が生じるまでに聴取開始から最低150秒かかるという遅れ時間を確定し
ました。ただし，効果量が非常に小さいため，現在はさらに長い聴取区間を用いた確認実
験を行っています。


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