Two synchronized radio towers, Tower 1 and Tower 2, are transmitting signals at the same frequency of 400 Hz. Tower 2 is located exactly 1.0 m north of Tower 1. An observer is located somewhere along the line joining these two towers. If 'y' represents the distance from the observer to Tower 1, then find all possible values for y which would result in destructive interference at the observer's location. Consider the speed of sound in air to be 340 m/s.