A microphone is undergoing simple harmonic motion (SHM) above a 440-Hz sound source as shown in the figure. The period of the microphone's SHM is 2.0 s and there is a difference of 2.1 Hz between the highest and lowest recorded frequencies. Ignoring any reflections of sound in the room and using the velocity of sound in air at room temperature, determine the amplitude of the simple harmonic motion.