At the SLAC National Laboratory (USA), a group of researchers led by Gabriel Blage managed to achieve in practice the calculated sound loudness limit. They used a Linac Coherent Light Source (LCLS) X-ray laser to target microjets of water, generating shock waves in them. Thus, they managed to achieve a sound pressure intensity of 270 dB.
Since sound is not an independent phenomenon, but a kind of side effect of impact on the environment, it can only form in a small range of conditions. If there are no vibrations in the environment, it is stationary - this corresponds to zero loudness level. When an external force is applied, we can provoke vibrations, increasing their intensity and volume. But when the level of 194 dB for air and 270 dB for water is reached, such pressure will begin to destroy the medium itself, which conducts oscillations - the movement of particles will continue, but there will be no sound.
The researchers used an X-ray laser to fire pulses of ultra-thin jets of water with a diameter of 14-30 microns. Under the influence of radiation, the liquid instantly evaporated, generating a shock wave, which began to move along the jet. The result was a combination of high and low pressure zones, which is a sound wave from a physical point of view. And its loudness was the maximum possible for these conditions - 270 dB.
The purpose of the experiment was not to reach the loudness limit - but to seek evidence that this is the limit. With an increase in the effect on water, instead of simple evaporation, it began to turn into microbubbles filled with steam. They formed and immediately collapsed (this process is called cavitation - ed. Techcult), which created pressure drops, but a full-fledged sound wave could no longer form under such conditions. What was required to be proved within the framework of this experiment.