Brown Note Test — Myth Explained
Explore the brown note myth with sub-20 Hz infrasound demos, speaker excursion notes and honest limits. Science, not pranks. Free in your browser, no download.
Protect your hearing. Start at a low volume. Never raise the volume to make a tone audible. Levels are shown in dBFS, relative to full scale — not SPL.
How it works
Synthesizes low sub-bass and infrasonic frequencies (5 Hz to 30 Hz) with speaker hardware excursion protection, paired with empirical acoustic physics and MythBusters research debunking the laxative urban legend.
The legendary “Brown Note” is one of the most persistent urban myths in modern audio lore.
The Physics of Infrasound & Cone Excursion
Infrasound refers to acoustic waves oscillating below the nominal human hearing boundary of 20 Hz. Generating low-frequency sound requires displacing volume of air proportional to the square of the wavelength:
$$\text{Displacement} \propto \frac{1}{f^2}$$
To reproduce an inaudible 7 Hz tone with the same acoustic output as a 56 Hz bass note, a loudspeaker cone must move with 64 times greater displacement ($\Delta x$). Because small computer speakers and earphones have voice-coil travel (Xmax) of only 1–3 millimeters, driving them with sub-10 Hz signals bottoms out the voice coil against the magnet backplate, resulting in harsh clipping and potential driver damage.
What Does Extreme Infrasound Actually Do to the Human Body?
While the brown note’s laxative claim is false, intense infrasound (>120–140 dB SPL) does interact with human physiology:
- Vestibular & Balance System: Fluid within the inner ear’s semicircular canals can oscillate, causing motion sickness, mild vertigo, and disorientation.
- Chest Cavity Resonance: The human thorax has a natural resonant frequency around 50–60 Hz, where high sound pressure can cause sensations of chest tightness.
- Auditory Threshold: According to ISO 226 equal-loudness contours, human hearing does not simply shut off at 20 Hz, but our sensitivity falls drastically. Hearing a 7 Hz sound requires sound pressure levels exceeding 110 dB SPL.
Frequently asked questions
What is the "Brown Note"?
The 'Brown Note' is an urban legend alleging that an infrasonic tone between 5 Hz and 9 Hz at high volume creates resonant vibrations in the human digestive tract that cause involuntary defecation. This claim has been scientifically disproven by numerous acoustic and biomechanical studies, including full-scale field tests by MythBusters.
Did MythBusters test the Brown Note?
Yes. In MythBusters Episode 25 (2005), Adam Savage and Jamie Hyneman tested custom ultra-high-output Meyer Sound subwoofers tuned specifically to frequencies between 5 Hz and 9 Hz at sound pressure levels up to 160 dB SPL. Despite chest resonance and minor discomfort, no loss of bowel control occurred in any subject.
Why do my speakers buzz when playing a 7 Hz tone?
Standard desktop speakers and headphones cannot reproduce a 7 Hz acoustic wave because their drivers are too small to displace sufficient air volume, and their enclosure tuning rolls off below 40–50 Hz. The buzzing sound you hear is severe total harmonic distortion (THD) — overtones at 14 Hz, 21 Hz, 28 Hz, 35 Hz — and voice coil rattle, not the 7 Hz fundamental.
What is the brown note frequency?
Stories usually place the mythical brown note between 5 and 9 Hz, deep in infrasound below normal hearing, though no single agreed frequency exists because the effect itself is unproven. This page lets you explore those sub-20 Hz tones safely at modest volume and see why small speakers cannot reproduce them.