A new method for measuring and visualising turbulences, e.g. vortexes, and acoustic sound waves in gases is described. The measuring effect is based on the path difference Δδ between two interfering laser beams. This difference results from changes of the refractive index n, caused by pressure fluctuations p(t) in a measuring gas. The method is practicable in both the audio and the ultrasonic ranges, as well as for spatially small turbulences. It is qualified for investigating and presenting numerous acoustic, fluidic and airborne sound phenomena.
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