A gas bubble in water sings loudly — this is Minnaert resonance: the heavy liquid prevents the bubble from compressing quickly, forcing it to vibrate. In air, there's no such effect: air is too light. But if you dress the bubble in a soft silicone shell, like rubber, it plays the role of the water mass. You get an 'elasto-bubble'. When a sound wave hits it, the walls obediently give way, similar to how water around a real bubble restrains it. The tiny sphere, it turns out, can resonate at frequencies hundreds of times larger than its size, absorbing sound almost perfectly. Using spectroscopy (precise analysis of sound vibrations), scientists confirmed: the wave's energy is completely converted into heat, irreversibly increasing entropy — a measure of molecular chaos. That's exactly why the sound doesn't come back. By changing the shell thickness and radius, the bubble is tuned like a musical instrument. From these bubbles, like pixels of silence, coatings are assembled that dampen engine hum at a given note, and acoustic filters for ultrasound. The simplicity of silicone brings these silencers out of the lab and straight into our homes, promising long-awaited quiet.
The loud noise near ship propellers is the sound of bubbles bursting underwater, and the same Minnaert resonance is to blame.