Sound is something most people simply take for granted. Different sounds are present throughout the day, and there’s no way of turning off hearing completely. Those who take the time to think about the science behind sound will find a very interesting topic in general.
This article attempts to not just define a sound, but explain how sound works. There are a lot of little things that go into the making of sound, and the processing of sound without even actively trying.
What Is Sound?
To put it in basic terms, the sound is the movement of air. Whenever a person hears something, it means that their ear is vibrating in a certain way.
Think about when someone talks, plays an instrument or makes any type of noise. The source making noise is causing air to move, which the air picks up on.
Sound originates from vibration. With vibrations, they will cause a fluctuation of air pressure, which is otherwise known as sound waves.
Each sound wave has highs and lows, not to mention different levels of depth. One motion of a sound wave is called a cycle, and the distance from the bottom to the peak is defined as amplitude. (source)
What Is Amplitude?
When examining amplitude, the simple definition is that it determines the volume of a sound. The greater the distance between the bottom depth to the peak, the larger the sound. These are large ripples in the airwaves, which are easily picked up by even people with poor hearing.
A human ear can only take so much amplitude without causing damage. Amplitude starts to fade away the further the source is from the person hearing the noise. (source)
What Is Frequency?
Frequency is what makes each sound unique in its own way. It is defined as the change rate of the air pressure. Human ears can pick up on a wide range of frequencies, and other animals have even larger ranges.
One of the best examples of frequency is looking at a dog whistle. These are whistles that are so high in frequency that human ears don’t pick them up, but dogs react to them.
How is Sound Measured?
The most common way to measure sound is in the form of decibels. The scale at its lowest to zero, which is extremely difficult for even people who have very good hearing to pick up. Conversations usually hang around 50 dB, and it starts to get uncomfortable when the decibels get above 100.
In some quiet rooms for recording and research purposes, people have found ways to make a room negative in decibels.
One of the best ways to interact with sound and understand how everything works is to use a tool online that allows for pitch, amplitude, frequency and other changes.
By altering the wavelength of the sound, a person can hear the difference and start to piece everything together. Sound is all about hearing in the first place, so reading about it can only do so much to help properly explain how it works.
Sound Absorption and Reflection
Sound is traveling throughout the air and bouncing off of everything in his way. Every object that has some type of mass will interact with the soundwave in some way.
The vibration of an object through sound is measured as the resident frequency of that object. If the sound bounces off, is considered a reflection. If the mass can absorb most if not all the sound, everything will sound much different.
Think about the difference between being in an empty auditorium, versus being in a recording studio with soundproofing material surrounding every corner of the room. An auditorium will have a decent echo, and every single noise will bounce off of the walls and amplify.
Reverberation is when the sound bouncing off of a mass combines with the original sound wave. This gives a different effect on the sound, in general, and distorts everything just a bit. The closer a person is to the source of the original wave, the less prominent the reflected wave will be. There is a reverb that goes on at sporting events outdoors as one very common example.
In a soundproofing studio, there is no sound bouncing off the walls. Instead, it is being absorbed, making for a very clear, pure sound from the voice, instrument or anything producing sound for that matter.
How Sound Changes From Far Away
One of the most important things to know about how sound works is the inverse square law. This explains that the further a sound wave travels, the less intense the pressure change is. For humans, this means that a sound becomes quieter when it is far away.
The reason why ears perceive it that way is that atmosphere changes become smaller and smaller with both distance and time. Energy eventually dissipates, since the sound occupies a little more physical space.