Can Sound Waves be Slowed?

TL;DR

This paper demonstrates that the speed of sound in dielectric fluids decreases under strong uniform electric fields, revealing a new way to control acoustic properties in such media.

Contribution

It introduces the novel finding that electric fields can slow sound waves in dielectric fluids, expanding understanding of electro-acoustic interactions.

Findings

Sound speed decreases in dielectric fluids under high electric fields.

Ferrofluids show a similar but weaker effect due to low permeability.

Electric fields can be used to modulate acoustic wave propagation.

Abstract

Dielectric fluids experience a striction force in the presence of an external electric field. Although the striction force on the entire body of the fluid is usually zero, it does contribute to its deformations. In this paper, I show that the speed of sound in dielectric fluids is reduced when they are exposed to uniform electric fields of sufficiently high magnitude. Ferrofluids also experience a similar striction force in presence of a magnetizing field. However, their low relative permeability makes the effect very small.