The Doppler Effect -- frequency of a bat reflected on wall 1. The problem statement, all variables and given/known data A bat flies toward a wall, emitting a steady sound with a frequency of 22.0 kHz. This bat hears its own sound plus the sound reflected by the wall. How fast should the bat fly to hear a beat frequency of 190 Hz? 2. Relevant equations Doppler Effect equations 3. The attempt at a solution I know this is a case of the Doppler effect, but I don't understand the variations of the equations in terms of when the source is stationary, listener is moving towards it, etc. I also understand that the frequency the bat emits will be different than the frequency rebounded by the wall. I kind of need to be walked through this one, because all of the explanations I've seen thus far aren't really getting through... Thanks!