The Doppler Effect

The Doppler effect one of the most interesting phenomena related to sound. In order for the Doppler effect to be observed, something must be producing a constant sound while moving relative to an observer. The result of this is something that many people have experienced or can easily perceive. You may have noticed when an ambulance passes by you on the road that its siren seems to change pitch. Interestingly, the pitch of the siren will seem constant to the person driving the vehicle. The pitch variation that you perceive is a result of the Doppler effect.

What causes the changing pitch of this sound is the movement of its source. The siren produces a sound of a constant frequency, but its distance relative to you changes, which effectively changes the wavelength of the sound wave that is generated. Because the speed of sound is constant and proportional to wavelength * frequency, the changing wavelength causes the frequency to change. This is the root cause of the Doppler effect. The way we perceive the pitch of sound is related to the frequency, so this explains how we can hear the Doppler effect as it applies to sound waves. The Doppler effect is also present in light waves, a characteristic that is critical in the study of astronomy. As my blog focuses on sound, I will not go into depth about this aspect of the Doppler effect, but the this source provides good introductory information if you are interested.

As I begin my second semester, the focus of my studies is shifting toward the recording and reproduction of sound, as well as the digital processing of sound. The Doppler effect exists in the reproduction of sound in certain amps and speakers. Leslie cabinets, commonly used amplifiers for Hammond organs, rely on rotational motion in the production of sound. This gives them a unique and often desirable quality for some musicians. Soon, I will analyze the changing frequencies of sound produced by a Leslie cabinet as an example of the Doppler effect.

Works Cited:
"The Doppler Effect." The Doppler Effect. Physics Classroom. Web. 11 Jan. 2016.
"Doppler Effect." Hyper Physics. Web. 11 Jan. 2016.