This paper investigates the effects of the surface roughness on the flowfield and aero-acoustics of a CNC-milled and 3D-printed converging nozzle at relatively large Reynolds number (Re = 400,000 -- 620,000). A novel nondestructive scanning method is used to quantify the surface roughness of both nozzles. A comparison of the maximum surface roughness reveals that the 3D-printed converging nozzle has a rougher surface. Pressure measurements, images from the Schlieren system, and acoustic data are acquired from the two nozzles installed on a nozzle test apparatus and compared. Experimental results show that the 3D-printed converging nozzle performs similarly to the CNC-milled converging nozzle, except that it has a larger tonal noise at a slightly higher frequency. The comparisons demonstrate that the 3D-printed converging nozzle can be employed to quickly demonstrate and verify novel ideas and concepts in the pedagogy and research at relatively large Reynolds number.