In the first part of this activity, visitors will be able to observe the movements of the air around us. These movements, which are usually invisible, will be revealed using an optical method. The programme includes cascades of cold air in the surrounding air, wisps of heat emanating from a hand or even the observation of whirlpools! The second part consists of making visible the multiple vibrations that run through a stringed instrument. These movements, which are far too fast to be detected by the naked eye, are measured by laser vibrometry. In this way, the creation of sound in a musical instrument can be visualised live, enabling us to learn more about how it works.