Depending on the year model of the car, it might not make that sound. It wasn't required on some of the earlier EVs, which could be eerily quiet. I believe it's required by law on newer models. Pre-2016 Volts has a "pedestrian horn button"; 2016 and newer Volts play a noise continuously as lower speeds. (My Uncle says it sounds like the warp drive hum on the original Star Trek Enterprise.)