Your Ears Can Almost Hear Air Molecules

Silence is not silent. The air around you is a crowd of molecules hammering on your eardrum at random, and that hammering is a real, faint hiss. Your hearing is sensitive enough to sit only a little above it. An ear much more sensitive than yours would not pick up new sounds from the world - it would pick up the air itself.

At the quietest sound you can detect, your eardrum moves by less than the width of an atom, pushed by a pressure change under a billionth of the atmosphere's. Meanwhile the air's molecules fly at about 470 metres a second, faster than a jet airliner, and their uneven hits set the eardrum trembling on their own. That trembling is a floor no detector sitting in room-temperature air can get beneath. Even the quietest room ever measured, which absorbs everything else, cannot get below it.

How close is "almost"? Estimates run from right at the floor to about 20 decibels above it, depending on the frequency band and the model. Close, not touching.

Sources, in the order the video uses them:
Hearing sits near the thermal floor: threshold sound carries "only a few tens of times" the thermal energy, and Brownian motion of air molecules causes pressure fluctuations at the eardrum; eardrum motion at threshold is of "picometer dimensions" - Reichenbach & Hudspeth, Rep. Prog. Phys. 77 (2014), author version: https://arxiv.org/pdf/1408.2085
The ear's sensitivity lies "within an order of magnitude" of thermal noise - Kunchur, Applied Acoustics 211 (2023), author version: https://arxiv.org/pdf/2307.00084
The close end of the range: a model eardrum puts thermal noise at about -3 dB SPL, roughly at threshold (a model with a fitted damping term, not a measurement) - Harrison, arXiv 2009: https://arxiv.org/pdf/0910.3170
Threshold air motion about a tenth of an atomic diameter, pressure changes under a billionth of atmospheric pressure - HyperPhysics, Georgia State University: http://hyperphysics.gsu.edu/hbase/Sound/earsens.html
Air molecules at about 470 m/s: our kinetic-theory arithmetic for nitrogen at 20 C (mean speed, sqrt(8kT/pi m)); a jet airliner cruises at roughly 250 m/s.
The quietest room: Microsoft's Building 87 chamber at about -20 dB against a Brownian-motion floor of about -23 dB - Microsoft: https://news.microsoft.com/stories/building87/audio-lab.php
The Guinness record, -20.35 dBA, about 20 dB below the threshold of human hearing - so nobody in that room hears the air - CNN, 2018: https://www.cnn.com/style/article/anechoic-chamber-worlds-quietest-room/index.html