The Burnett equations are consistently reformulated as a linearly stable first order system. The equations are then applied to study the nonlinear evolution of a sound wave. The initially sinusoidal wave is nonlinearly distorted and a shock wave develops. The shock is gradually dissolved by dissipation and a sinusoidal wave of smaller and decaying amplitude emerges. The amplitude of this old age solution is compared with the classical results from the Burgers equation of nonlinear acoustics and systematic deviations are found.