An array of cylindrical roughness elements was used to reduce the tonal noise introduced by the separation bubble over a NACA 0012 airfoil at low angles of attack. Experiments were performed for three configurations: a baseline smooth airfoil, and two with rough surfaces, one with roughness elements at only one of the airfoil surfaces, and the other with roughness elements at both airfoil surfaces. A row of spanwise periodically spaced cylinders was placed close to the mid-chord position in order to induce streaks that render the bubble three-dimensional, decreasing separation and stabilizing the Kelvin-Helmholtz modes of the separated shear layer. Our results show a decrease, and in some cases total suppression, of the tonal noise at Reynolds numbers ranging from 0.8×105 to 2×105, and angles of attack ranging from 0 to 4 degrees. Wake-rake measurements of the drag were performed to understand the aerodynamic penalties caused by the presence of roughness elements, revealing slight drag increases.