Sound is created by pretty much anything that vibrates quickly, whether that be guitar strings or a drumskin, to the very vibrations of the earth that we call earthquakes. A sound’s loudness, its intensity as one could call it, is measured in decibels. How often the source of the sound vibrates is called its frequency, and the higher this is, the more high-pitched we perceive the sound to be. It’s measured in hertz. The human range of hearing is between 20Hz and 22kHz. Anything below is called infrasound, and anything above is called ultrasound. Sounds come in the form of waves, and the more compressed it is, the higher the frequency, and vice versa. This diagram summarises it quite nicely:
The Doppler Effect
The Doppler Effect is an interesting consequence of sound coming in this form that you can experience in your day-to-day life. When you’ve heard an ambulance go by with its sirens blaring, you might have noticed that as it gets closer, the pitch of the siren rises. Conversely, as it moves away from you, it gets lower until it moves out of earshot. This is due to the waves becoming more compressed relative to you as the ambulance approaches, and then uncompressing when the opposite happens.
In TV And Film
Audio is sound that is that comes from things such as transmissions, recordings and electronic devices. It is a very important aspect of shows and movies, being just as important as the visuals. There are different kinds of audio used in this area, such as foley sound, which is separately recorded to be synchronised with the video, and location sound, which is ambient background noise recorded at the shoot, but these are just two very broad categories. There is also a bunch of equipment that’s necessary for recording high quality audio, including, but not limited to, a dead cat, which is placed on a microphone to muffle unwanted background noise, and boom poles, which allow you to extend said microphone above shots where you can get a better recording without having it be visible.