A speaker on the edge of a well emits a sound at 500 Hz when it's accidently knocked over and falls into the well. As the speaker is falling, sound is being emitted downwards and reflected off the bottom of the well, traveling back upwards towards the speaker and producing beats. After the speaker has fallen some distance, it is moving at 10 m/s. What is the beat frequency created by the interfering sound waves at this point in time? Assume the speed of sound is 340 m/s.