On the show The Big Bang Theory, Sheldon goes to a Halloween party and dresses as the Doppler effect. he explains his costume to people by giving them the definition "its the apparent change in the frequency of a wave caused by the relative motion between the source of the wave and the observer". throughout the episode he also makes the noise of a car going by when people try to guess what his costume is. This noise he makes is a clear example of the Doppler effect because it sounds louder in the beginning and then fades away. This occurs when a siren of a police car or fire truck passes due to the Doppler effect.