Hi all, I was rather hopeing that someone here may know of a way to accurately measure the frequency of a sound wave? The reason I need to be able to do this is to investigate the doppler effect. I am able to measure the start frequency accurately using the following piece of software: http://www.visualizationsoftware.com/gram.html However, I am unable to accurately measure the change in frequency as I move a sound source of, for example, 12000Hz toward a microphone. Using the doppler equations I end up with the movement of the sound source of anything from 20m/s to 120m/s - obvously far too high. So, does anyone have any suggestions how I can achieve an accurate measurement of the change in frequency? Kind Regards, Richard.