The Spectrum of Sound Frequency: How is it Measured?
Have you ever wondered what kind of range we have as humans? While dogs, cats, bats and other animals have incredible hearing, today we will learn about our hearing as humans.
When listening to music, it’s nice to experience a balance of sound and depth to the music. So, how can we measure this and get a good balance of sound?
From a sound frequencies perspective, it’s important to understand how these sounds play a part in our ability to hear the quality of sound and how we measure it.
So, to understand the spectrum of sound frequency, we need to explore how we hear, what a sound frequency is and how we use the spectrum.
How Do We Hear?
It’s amazing how a sound wave is heard by humans and how the hearing system’s speech sound frequency is then understood as words by the brain.
So, how do we hear those sounds?
The outer ear takes in the sound, which travels through the ear and vibrates the three smallest bones in our body, the stapes, malleus and incus. These bones transfer the sound to the inner ear, stimulating the cochlea, which is the most sound-specific organ in our body.
The cochlea is filled with fluid and when the sound waves vibrate the fluid, it creates a wave within the organ. This stimulates thousands of hair cells that work to convert the sound waves we hear into electrical energy that the brain can then comprehend.
Different sound waves stimulate specific regions of the cochlea and allow us to differentiate and distinguish sounds from one another.
What Does Sound Frequency Mean?
Now that we have an understanding of how we hear, we can look into the spectrum of sound frequency.
The scientific definition of a sound frequency is the number of times per second that a sound pressure wave repeats itself.
In our world, we know that sounds do not occur in isolation. The spectrum of sound frequency is measured in Hertz (Hz) and can illustrate what the human ear can understand and make sense of.
For example, when a baby is born, the sound frequency range they can hear is between 20Hz and 20,000Hz. Below is a graph of where human hearing sits in the sound frequency range when compared to other animals, such as whales and bats.
A sound spectrum displays the different frequencies present in a sound. The sound of a violin playing draws on a combination of sound frequencies that come together to form music. To understand the depth of sound, it’s important to look at all the sound frequency vibrations as a unit, instead of single sound frequencies.
A way of understanding these sounds is by looking at the sound spectrum. A technique used to represent short bursts of sound frequencies and analyse the vibrations of each frequency.
How is The Spectrum of Sound Frequencies Measured?
The spectrum of sound frequency can be presented as a graph where the pressure of the sound is measured in decibels and the vibrations are measured in Hertz (Hz) or kilohertz (kHz = 1000Hz).
The spectrum of sound frequency is also known as the audio frequency spectrum. The graph shows the distribution of energy as a function of frequency for a particular sound. The spectrum is captured by using a microphone to capture the sound pressure that needs analysis and then records a snapshot of the sound frequency over time.
This information is then recorded on a graph. Below is a graph of a sound wave mirrored with a sound frequency spectrum for a tuning fork, flute, violin and singer. It’s clear by looking at the sound frequency spectrum that different sounds have different weights across the frequencies measured. The tuning fork is more low frequency and the violin is more active in the mid-high frequencies.
Why do we Use The Sound Frequency Spectrum?
By looking at a sound frequency spectrum, we can break the sounds into seven bandwidths and have a better understanding of the distribution of sound across 16,20,000Hz.
The table below shows the different categories of a sound frequency spectrum allowing us to see the balance of a sound.
Source: CUI Devices
The sub-bass sound frequencies are usually felt more than heard and instruments such as tuba and bass guitar are found in this range.
The bass determines the depth and thickness of a sound and is where the frequency in spoken speech is found.
The low to mid-range contains lower frequency harmonics of music with brass instruments falling into this category.
The mid-range introduces high frequencies with instruments such as the violin being heard in this range.
The high-mid range is where human speech is most sensitive.
The presence range is responsible for the clarity and definition of a sound with harmonics of instruments such as the piccolo.
The brilliance range is where sound frequencies become more shrill with very high sound frequencies and sound like symbols chiming in this range.
To Sum It Up
By looking at the sound frequency spectrum, one can both understand and manipulate sounds to be more balanced and in line with how they like to listen to sounds.
It allows for a better understanding of how sounds are interpreted when we listen to them.
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