The Doppler Effect is the change in frequency of a wave. The video above gives a good summary of how the Doppler Effect explains the difference in sounds you hear from different points. When a sound is being produced from a resting position and not moving, the spheres of vibrations are equal and the energy produced is distributed evenly. However, if the sound waves are moving, the vibrations are more angled to the front, giving anyone that is in the direction of the travelling sound hears a higher pitch. If someone is standing behind the travelling sound, the pitch is lower due to receiving less waves to the ears. Motion creates the change in pitch because of the observed frequency between the observer and the source of the sound waves. Since sound waves are mechanical waves, they have to travel through a medium: air. Wind is a factor in how the pitch of the sound is perceived due to the sudden change in direction of wind. It's not only the moving sound waves or the medium's motion, but also the observer's movement. If someone is walking in the opposite direction than the sound waves are moving, that person be even further away from the source of the sound, meaning that the spheres have a less impact of sound, making the observer perceive a lower pitch of sound. In summary, the way that the ear perceives the pitch/sound is from the results of the motion of the medium, the motion of the sound waves' origin, and the motion of observer.
Electromagnetic waves are waves that are able to transfer energy without using a medium. An example of electromagnetic waves are light waves. The light waves that the Sun produces is able to travel through space an reach space. If electromagnetic waves did not have the ability of travelling through space, there would be no life on this Earth. Not only that but most of the world today is based on technology. Without electromagnetic waves, we wouldn't be able to watch television shows, listen to the radio in our cars, or call/text someone on our cell phones. The radio waves that are sent out to these devices are electromagnetic waves.
Magnetic waves are waves that travel through a medium (matter) in order to transfer energy. An important form of a magnetic wave is a sound wave. Sound waves are vibrations that travel through the air (its medium) and vibrate our eardrums, sending signals to the brain which interpret it as "sounds". Without sound waves, we wouldn't be able to hear anything such as music or lectures.
