Abstract: Observed cases of residual intensities between convergence zones of propagating underwater sound, in the absence of a bottom slope must be explained, and are illustrated here, by the effects of sound penetrating into the ocean floor and returned back into the water column by the presence of an upward-refracting bottom sound speed gradient. It is shown that depending on the geometry and the bottom properties, this mechanism can lead lo quite dramatic examples of inter-convergence zone residuals, providing an interpretation of observed effects of this kind.