This Is Sound
We are all sound enthusiasts in some way or the other, but most people don’t really know what sound is, or how it works. Let’s go through the basics of sound!
What is sound?
All sounds are invisible vibrations traveling through the air as sound waves. Sound waves are caused by the vibrations of objects and radiate outward from their source in all directions. As sound travels, it reflects off objects in its path, creating further disturbances in the surrounding air. When these changes in air pressure vibrate your eardrum, nerve signals are sent to your brain and are interpreted as sound.
All sounds are made up of different frequencies. We can describe this as the pitch of a sound. The frequency of a sound affects the pitch that it is heard at. The sound a whistle makes when it’s blown is an example of a high frequency pitch whereas the noise made when banging on a drum is an example of a low frequency pitch. Frequency is measured in cycles per second, or hertz (Hz). Humans have a range of hearing from 20 Hz (low) to 20,000 Hz (high).
Amplitude (or intensity) refers to the strength of a sound wave, which the human ear interprets as volume or loudness. People can detect a very wide range of volumes, from the sound of a pin dropping in a quiet room to a loud rock concert. Because the range of human hearing is so large, audiometers use a certain scale to make the units of measurement more manageable. The result – the sound pressure – is measured in decibel (dB).
The decibel measures sound pressure or electrical pressure levels. Different kinds of decibels are measured depending on what you aim to measure. For instance music, dBA is used, and it means that you are measuring the harmful frequencies (the treble). If you want to measure the actual perception of the ear, you use dBC. Changes in decibels differ from what you would expect. For every 3 dB increase, the sound pressure is actually doubled. For example 53 dB is twice as strong as 50 dB.