Our setup

To achieve results for our research question, an experimental setup was constructed in which a single droplet, with controlled size and release height, could be dropped into a liquid reservoir. An acoustic sensor (microphone) was positioned below the surface of the liquid to capture the sound signal resulting from the impact and any subsequent bubble formation. Simultaneously, a high-speed camera was used to visually record the behavior of the droplet and the bubble.

A key requirement for successful sound detection was the creation of a precise and consistent droplet. If the droplet was too small, misshaped, or released at an incorrect velocity, no bubble would form, or a bubble would form that failed to produce any significant acoustic signal. Therefore, careful tuning of both droplet shape and falling height was essential. This was achieved using a finely adjustable droplet dispenser, combined with variations in surface tension, viscosity, and release height of the fluid.