Extremes · spectrum
Infrasound and ultrasound beyond the musical set
Below 20 Hz and above 20 kHz: perception, hazards, myths, and art.
Dual lens. Science pane = measurable / historical fact pattern.
Mystic pane = living myth, ritual, and cultural meaning. BBM is not a medical device.
◈ Science
Infrasound (<~20 Hz) can be felt more than heard; industrial and natural sources exist; very high levels can cause discomfort. Ultrasound (>~20 kHz) is used in imaging and industry. Consumer “silent subliminal” ultrasound claims are mostly bunk for headphones.
✦ Mystic / Mythos
Ghost-hunter and ritual lore sometimes blames infrasound for dread. Possible physiological contribution in some environments; not a default spirit detector.
Operator tip. Headphones for binaural difference tones.
Musical pitch (432 / solfeggio fundamentals) is a different control axis from beat frequency (delta→gamma).
Explore freely; extraordinary healing claims need extraordinary evidence.