Doppler Shift App is a visualization/simulation of Doppler shifts of sound waves. The user can control the sound speed, frequency, velocity of source or receiver.
The chart recorder at the bottom displays the wave crests as detected by receiver (the ear) and their frequency. It also displays the instantaneous wavelength in the ear is at rest.
The user can drag the source or the receiver to any location in the display. The user can also cause the source and/or the receiver to move by choosing the appropiate mode in the drop-down box, and can choose the velocity of each.