

Inaudible High-Frequency Sounds Affect Brain Activity: Hypersonic Effect (2000) - twa927
http://jn.physiology.org/content/83/6/3548

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rd108
Apparently the high frequency alone did not effect brain activity unless
coupled to audible or "low frequency" sounds.

I wonder if the two frequencies interact to form beat frequencies or complex
wave superpositions in the audible range. That would jive with this
description of the Japanese researchers' instrument:

"Traditional gamelan music of Bali Island, Indonesia, a natural sound source
containing the richest amount of high frequencies with a conspicuously
fluctuating structure, was chosen as the sound source for all experiments."

Alpha brainwaves, which were seen when both high and low frequencies were
combined, correlate with being "relaxed and alert". Interesting findings.

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seanp2k2
Welp, I guess here's your evidence for 24/192 audio being not-useless.

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droidist2
Ohh, beat me to it. Nice.

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stephengillie
I'm not sure how related this is, but I used to get bad headaches from the
ultrasonic sensors on my self-driving RC car project. I always wondered if
others were affected, and how that impacted other ultrasonic-based projects.

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underwater
I worked on a project where I used ~20kHz tones to transmit data between
devices. I also got headaches.

