Figure 7.

(Color online) (a) The pressure fluctuations at the dynamic boundary ($z=1.4\mathrm{\hspace{1em}}\mathrm{cm}$) is shown over a time period of $75\mathrm{\mu }\mathrm{s}$. Four different phases, each with increasing average pressure amplitude, can clearly be seen. Each phase corresponds to the time it takes a reflected wave to reach the boundary $(t_1=\frac{L}{c},t_2=\frac{3L}{c},t_3=\frac{5L}{c}$ and $t_4=\frac{7L}{c})$. (b) The contour graph clearly shows the effect of the destructive interference of the reflected wave in the regions $t_1<t<t_2$ and $t_2<t<t_3$. When $t>t_3$, the pressure amplitude reaches a steady state.