Comment on "Linear and nonlinear frequency shifts in acoustical resonators with varying cross sections" [J. Acoust. Soc. Am. 110, 109-119 (2001)].

The effects of the shape of the container on nonlinear resonant oscillations have been of interest for the past decade. Resonant oscillations in a closed straight tube can contain shocks, but for some tube shapes shock formation can be prevented. How the magnitude of the variation of the shape from a straight tube affects the prevention of shocks is discussed. Criteria to determine whether tuning curves bend right or left are addressed, including that proposed by Hamilton et al. ["Linear and nonlinear frequency shifts in acoustical resonators with varying cross sections.