The Parameter \(B/A\)

The ratio \(B/A\) , which has become a traditional measure of acoustic nonlinearity associated with the equation of state for a fluid, has its origin in the Taylor series expansion of variations of the pressure in terms of variations of the density. Relations defining \(B/A\) for liquids and immiscible mixtures are derived, and explicit expressions are presented for perfect gases and longitudinal waves in isotropic solids. Methods for measuring \(B/A\) in liquids are described. Tables are provided with numerical values of \(B/A\) for various fluids, liquefied gases, and biological tissues, and for proteins and amino acids in aqueous solutions.