What do decibels and frequency mean?
Posted on Sep 2, 2016
When it comes to looking after our hearing, the first step of action to take is knowing why it's so important for our health. By understanding why we take precautionary means, we can make informed decisions when it comes to sound exposure.
You'll have come across the terms frequency and decibels by now. While both are obviously associated with sounds, do you know what each one really means?
The measurement of decibels
Decibels, commonly shortened to dB, are a unit to measure the volume of sound. The decibel scale starts from 0 dB, which is the threshold of sound for the human ear. When looking at the measurement of dB, it depends on context.
Sound at 0 dB doesn't mean that no noise is present, rather, it's the quietest sound that the human ear can pick up. In order to accurately calculate the volume of sounds we hear into digits, a logarithmic scale is used rather than a linear one. That means if a noise reads at 3 decibels higher, it's double the sound intensity.
At 0 db, it's almost complete silence. A whisper will read around 15 dB, whilst a normal conversation is approximately 60 dB. To scale, a rock band's volume can hit 120 dB, and though it reads double on the decibel scale, a rock concert is not twice as loud as a mere normal conversation!
Finding out about frequency
To understand what frequency means when referring to sound, we have to first explore how sound works. When a noise is made, it creates a vibration – the size of this vibration is called amplitude, and the speed of the vibration is called frequency.
Larger vibrations means the sound is louder – called high amplitude – whereas high frequency refers to a higher pitch of sound. Frequency can only really be applied to useful sounds, such as music.
When those delicate hairs in our inner ear are damaged, either though excessive sound exposure or age-related hearing loss (called presbycusis), we lose our ability to hear sounds at a higher frequency. So, in a hearing test, it makes sense to calculate hearing loss by exposing someone to a series of beeps at increasing frequency, and logging down their threshold – this is how changes in a person's hearing is determined as hearing loss.
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