Question Video: Calculating the Wave Fronts of a Sound from a Moving Source Passes by a Moving Observer Physics

A person moves toward a source of sound waves, as shown in the diagram. The sound source starts to emit sound at the same moment that the person starts to move. The sound from the source moves a distance equal to the wavelength of the sound wave in a time interval 𝑡. How many wavefronts from the sound source will have reached or passed the person by the time that the person has moved from their initial position to the point 𝑃?