Rotary Woofer (2006)
&gt; However nothing existed to produce significant enough output to change this belief.<p>I thought it was more accurate to say that the lowest frequency a human can perceive as sound is also the threshold between determining if a sequence of pulses is a sequence of distinct events and one continuous sound, whose period is around 5ms (or 20Hz) and this is pretty easy to verify experimentally, even with woofers that can&#x27;t produce a pure sine below 20Hz.<p>That said there is another factor which is that we don&#x27;t just experience pressure waves in air with our ears, but with our full body of senses. And if you can definitely be impacted by infrasound even if it isn&#x27;t just vibrating your ears, since it will absolutely vibrate your chest cavity and the rest of your body and you can feel that in your bones (or so to speak).<p>There&#x27;s also a long history of scientific&#x2F;pseudo scientific and almost apocryphal stories about infrasound. Off the top of my head I&#x27;ve heard of fans in a building causing subsonic vibrations that disoriented people, subsequent research into weaponizing it, whistles that were designed to vibrate below the threshold of hearing, the legendary &quot;brown note&quot; (a sound low enough and powerful enough to cause evacuation, of a building or a person) and even Havana syndrome was allegedly attributed to infrasound.<p>It&#x27;s very interesting to use a fan to create such waves when an electromagnetic piston might fail. But I wonder how useful it is since making a piston vibrate at low frequencies isn&#x27;t that hard, it&#x27;s enclosing it that is the problem. I suspect a large enough enclosure with a big enough woofer and enough power in an amplifier (eg, a commercial subwoofer) can do just as well without being so exotic as to require custom electronics.