Flow cytometry concepts are modified to enable dynamic characterizations of particles to be obtained using optical scattering data. Particles in flow will be introduced into a sample volume. Light scattered by a particle in the sample volume is collected and analyzed. What differentiates the concepts disclosed herein from conventional flow cytometry is the use of an acoustic source that is disposed to direct acoustic energy into the sample volume. As the particle passes through the sample volume, it responds to the acoustic energy, causing changes in the light scattered by the particle. Those changes, which are not measured during conventional flow cytometry, can be analyzed to determine additional physical properties of the particle.