We have irradiated slant‐angle‐deposited metallic films on sapphire substrates with pulses of incoherent phonons and observed voltages in the plane of the sample. These voltages are very similar in character to those previously observed using laser irradiation as the excitation source. The new data prove unequivocally that these as well as our previously observed voltages in metal films are purely thermal in origin, consistent with a thermoelectric model.