This paper comments on a number of inaccuracies in the recently-published article by Balint et al. [S. Balint, A.M. Balint, M. Darau, Linear stability analysis of a non-slipping mean flow in a 2D-straight lined duct with respect to modes type initial (instantaneous) perturbations, Appl. Math. Model. 35 (2011) 1081–1095], concerning initial value acoustic perturbations to a steady mean nonslipping flow in a 2D duct: in particular, the neglect of antisymmetric solutions, and their comments on stability. Here, their dispersion relation is briefly rederived and simplified, two numerical results are presented demonstrating the existence of antisymmetric solutions in a specific case, and the inaccuracy in their comments on instability is highlighted.