The response of low Reynolds number air jets to acoustic modulations is investigated with systematic experiments. Flow transfer functions, power spectral densities of the perturbations plotted in the form of space-frequency maps, instantaneous jet images recorded using laser tomography, and phase-conditioned velocity fields serve to identify the different regimes of motion. Results indicate that five regions can be distinguished in a diagram where the jet Strouhal number StD serves as a horizontal coordinate while the shear layer Strouhal number St