Abstract
A device measures the propagation time for an acoustic wave in a continuous phase of a two-phase mix (28) comprising the continuous phase and a dispersed phase forming droplets (40) in the continuous phase. The device comprises an electro-acoustic transducer (12) capable of emitting acoustic waves (30) and outputting a reception signal of reflected acoustic waves, a signal pulse generator capable of determining a propagation time starting from signals output by the transducer, and an acoustic lens for focusing acoustic waves and the frequency of the acoustic waves being adjusted to cause reflection of the waves on the droplets of the dispersed phase, essentially located within a focusing area.