低音刺激でダンス盛り上がり　加研究で実証

【ワシントンＡＦＰ＝時事】ＤＪが低音の音量を上げればダンスフロアの客が盛り上がり、体の動きも激しくなることを、エレクトロニックミュージック好きは経験的に知っている。だが、そうした反応は意識的な反応なのだろうか。（写真はナイトクラブで踊る人）
　カナダの研究者がこのほど、これまで科学的に示されていなかった、低音と身体の動きの関係を明らかにした。研究結果は７日、学術誌カレント・バイオロジーに掲載された。
　研究では、エレクトロニックミュージック・デュオ「Ｏｒｐｈｙｘ」のライブの観客１３０人のうち約６０人に、身体の動きを計測するための動作検知ヘッドバンドを装着してもらい、人間には聞こえない超低周波音が流れるスピーカーのスイッチを入れたり切ったりした。
　その結果、超低周波音が流れると、身体の動きが１２％ほど活発化することが示された。
　被験者に記入してもらった質問票から、音の変化には気付かなかったことが確認された。これにより、曲の盛り上がり部分に反応したのではなく、低音に反応して動きが激しくなったことが証明された。
　研究を率いたマクマスター大学のデービッド・キャメロン氏はＡＦＰに、人間が感知できない低音も、皮膚や前庭器官（内耳）などの感覚系を刺激していると語った。
　これら感覚系は運動系と緊密につながっており、感覚系を刺激することで運動系が活性化され、身体の動きも活発化すると研究チームは考えている。その際、精神作用や随意運動をつかさどる前頭葉は経由しない。キャメロン氏は「意識下のレベル」での働きだと指摘する。【翻訳編集ＡＦＰＢＢＮｅｗｓ】
〔ＡＦＰ＝時事〕（2022/11/09-15:04）

Electronic music lovers know the drill: as soon as the DJ turns up the bass, the crowd goes wild and dances with heightened enthusiasm. But to what extent is this a conscious reaction?
Researchers have taken a closer look at the relationship between bass frequencies and dancing, thanks to an experiment conducted during a real-life electronic music concert.
The results, published Monday in the journal Current Biology, showed that participants danced almost 12 percent more when researchers introduced a very low frequency bass -- one that dancers could not hear.
They couldn't tell when those changes happened, but it was driving their movements, neuroscientist David Cameron of McMaster University, who led the study, told AFP.
The results confirm the special relationship between bass and dance, which has never been scientifically proven.
- The pulse of the music -
Cameron, a trained drummer, notes that people attending electronic music concerts love when they can feel the bass so strong and tend to turn it up very loud.
But they are not alone.
In many cultures and traditions across the world it tends to be the low-frequency instruments like the bass guitar or the bass drum, that give the pulse of the music that gets humans moving.
What we didn't know is, can you actually make people dance more with bass? said Cameron.
The experiment took place in Canada, in a building known as LIVElab, which served both as a concert hall and a research laboratory.
About 60 out of 130 people who went to see a concert by electronic music duo Orphyx were equipped with motion-sensing headbands to monitor their dance moves.
During the concert, researchers intermittently turned very-low bass-playing speakers on and off.
A questionnaire filled out by concert-goers confirmed that the sound was undetectable. This allowed researchers to isolate the impact of the bass and avoid other factors, such as dancers reacting to a popular part of a song.
- Below the level of consciousness -
I was impressed with the effect, said Cameron.
His theory is that even when undetected, the bass stimulates sensory systems in the body, such as the skin and the vestibular system -- more commonly known as the inner ear.
These systems have a very close connection to the motor system -- responsible for movement -- but in an intuitive way that bypasses the frontal cortex.
He compares it to the way the body keeps the lungs breathing and the heart beating.
It is below the level of consciousness.
Cameron said the research team believes the stimulation of these systems give a little boost to your motor system. And that adds a little bit of energy and vigor to your real-world movements.
He hopes to verify this hypothesis in future experiments.
As for why humans dance at all, the mystery endures.
I've always been interested in rhythm, and especially what it is about rhythm that makes us want to move, in the absence of a specific function of dance.
Most theories revolve around the idea of social cohesion.
When you synchronize with people, you tend to feel bonded with them a little bit afterward. You feel good afterwards, said Cameron.
By making music together, that allows us to feel better together as a group, and then we function better as a group, and we can be more efficient, and we can have more peace.