While many standard measuring devices, such as rulers, are linear , the decibel scale is logarithmic. This kind of scale better represents how changes in sound intensity actually feel to our ears. To understand this, think of a building that is 80 feet tall. If we build up another 10 feet, the building will be Using the logarithmic decibel scale, if a sound is 80 decibels, and we add another 10 decibels, the sound will be ten times more intense, and will seem about twice as loud to our ears.
Sometimes we use different versions of decibels. While the dB scale is based only on sound intensity, the dBA scale is based on intensity and on how the human ear responds. Because of this, dBA gives us a better idea of when sound can damage your hearing. The cochlea is a snail-shaped organ inside your inner ear that allows you to hear. The cochlea can respond to a certain range of frequencies, or pitches of sound.
Read more about how we hear or watch a video on how sound travels to the brain. The cochlea responds best to frequencies in the range of human speech. In the frequencies that our ears respond to best, measurements for dBA are just as high as they are in dB. For instance, the high-pitched E string on a violin has very similar dB and dBA levels.
For instance, the lowest note on a tuba 16Hz will have a much lower dBA reading than a dB reading. Even small increases in dBA level can have a big impact on your hearing health. Although the ear can distinguish the rise in level between one or two pins dropping, it cannot distinguish between 10,,,, pins and 10,,,, pins or even 10,,,, because it is not a linear device. It can, however, distinguish the significant multiplying of the energy of the sound.
When you measure noise levels with a sound level meter, you measure the intensity of noise called decibel units dB. If you think about it, it would be very difficult to manufacture a sound level meter that had a linear performance, especially bearing in the mind the range of noise sources to be measured in a work environment.
It would be tricky to keep an eye on those 14 digits varying in front of you! So, to express levels of sound meaningfully in numbers that are more manageable, a logarithmic scale is used, using 10 as the base, rather than a linear one.
This scale is called the decibel scale. On the decibel scale, the quietest audible sound perceived near total silence is 0 dB. A sound 10 times more powerful is 10 dB. A sound times more powerful than near total silence is 20 dB.
A sound 1, times more powerful than near total silence is 30 dB, 40 dB and so on. When this sound is doubled this equates to a rise of 3dB decibels , using a logarithmic scale. In other words: every increase of 3 dB represents a doubling of sound intensity or acoustic power.
The use of the dB unit makes it easier to measure decibels and monitor sound changes if we use these rules. The table below summarises this:. Because sound pressure levels in decibels dB use a logarithmic scale we can't just add two dB readings together. Step 1: Find out the difference between two noise levels and then find the corresponding row in the left-hand column.
Sound can be measured with a device called a decibel meter. It samples and measures sound, giving a readout. Decibel meters also called sound-level meters can even be accessed on a smartphone through apps. Measuring the sound of an environment with a common device like a smartphone that many people always carry may help protect their ears more often. Sound is measured in units called decibels dB.
The higher the decibel level, the louder the noise. On the decibel scale, the level increase of 10 means that a sound is actually 10 times more intense, or powerful.
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