What Are Decibels, And How Are They Measured?

What are decibels, and how are they measured? Decibel scale, measurement units & sound intensity

The human ear is an incredibly flexible hearing device. It has a smart built-in mechanism that reduces its own sensitivity as the sound level goes up and it also has the extraordinary ability to handle a vast range of sound power levels. It can hear the sound of a coin dropping close-by as well as the booming of a jet engine miles away.

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In A Hurry?

If require the Best Hearing Protection for this item, and do not want to read the entire article, below are my recommended ear protection.

Which are the best Earplugs for Measuring Decibels?

For Measuring Decibels, the best ear plugs are REED Instruments R8060 Sound Level Meter with Bargraph.

However, this will depend on several things. If you use them a lot, for example, if it is your principal job, or perhaps just minor use. Also, if you want to use these ear plugs for other things

There are earplug options available, for example: Convenient Fitting, Noise Reduction Rating (NRR), Long-Lasting, Flexibility. As you can see, there is a lot in picking the best fit.

What is a decibel?

The decibel (symbol: dB) is a relative unit of measurement equivalent to one-tenth of a bel (B). It is used to exhibit the ratio of one value of a power or root-power quantity to another on a logarithmic scale. A logarithmic quantity in decibels is called a level. Two signals whose levels vary by one decibel have a power ratio of 101/10. Zero decibels (0 dB) is the lowest sound audible to a healthy human ear. From there, every increment of 3 dB means doubling of sound power or acoustic intensity.

Decibel’s definition originates from the readings of power in telephony of the beginning of the 20th century in the Bell System in the United States of America. One decibel is one-tenth (deci-) of one bel, named as a tribute to Alexander Graham Bell; however, the bel is rarely used. Today, the decibel is used for a wide spectrum of measurements in science and engineering, particularly in acoustics, electronics, and control theory. In electronics, the gains of amplifiers, attenuation of signals, and signal-to-noise ratios are usually measured in decibels.

Sound power and loudness

The relative loudness that we perceive isn’t something that can be objectively measured; it depends on the individual. Most of us identify a particular sound to be two times as loud as another one when they are about 10 dB apart; for example, you will find a 60-dB air conditioner twice as loud as a 50-dB refrigerator. Yet that 10-dB variation is actually a ten times increase in intensity. A 70-dB dishwasher will sound approximately four times as loud as the 50-dB refrigerator, when it comes to acoustic intensity, the sound it makes is 100 times as strong.

Here's another example: If the sound from one typewriter registers 60 dB, then ten typewriters clicking would register 70 dB (not 600 dB!), and they would sound only two times as loud as one machine. You would need 100 typewriters to attain a noise level of 80 dB, and together they would sound only four times as loud as a single typewriter.

The possibility for a sound to damage hearing is proportional to its intensity, not its loudness. That's why it's delusive to rely on our subjective perception of loudness as a sign of the risk to our hearing.

Noises For A Decibel Meter

The following infographic shows a list of the various noises when you are out and about. Any noise over 70-80db over a long period of time may cause damage to your hearing. A noise of over 120dB may cuase immediate harm to your ears

Here are some linear and non-linear sound levels in our circumambience :


Intensity (In watts per sq/m)

Type of sound



Dead silence



Soundproof room






Lecture room



Quiet room in a home



Restaurant/private office



Engaging in a conversation/ work office



Telephone bell/street noise



The noise inside of a car



The noise inside of a bus/truck



Electric saw



Orchestral music



Loud rock concert



Artillery fire (pain threshold)

Phons and Sones

The phon is a non-regular noise unit that is intended to reflect perceived loudness, and is based on psychoacoustic tests in which volunteers were asked to adjust the decibel level of a baseline tone of 1 kHz until it was the equal loudness as the signal being measured. So for instance, if a sound is 70 phons, that means it sounds as loud as a 70-dB, 1-kHz tone. The dBA scale is now largely used rather than phons.The sone is a more intuitive measure of loudness, because a doubling in the number of sones equals a doubling in loudness that you perceive(unlike the logarithmic phon scale). Noise levels of household fans are usually measured in sones.

A-weighting dB(A) and C-weighting dB(C)

Measuring noise levels relating to loud noise at work are usually given in dB(A) or dB(C) - those frequency weightings are applied to the decibel measurements (A and C frequency weightings), actually they are decibel scale readings that try to replicate the sensitivity of the human ear to various sound frequencies.
  • A-weighting (A-frequency-weighting): ‘A’ Weighting is predominantly used and covers the full frequency range of 20Hz all the way up to 20 kHz. The human ear is most sensitive to sound frequencies between 500 Hz and 6 kHz while at lower and higher frequencies the human ear is not that sensitive. The 'A' weighting adjusts the sound pressure readings to display the sensitivity of the human ear and is therefore mandatory all over the world for hearing damage risk readings.
  • C-weighting (C-frequency-weighting): The C-weighting is mainly focused at the effect of low-frequency sounds on the human ear.m Compared with the A-weighting it is essentially flat or linear between 31.5Hz and 8kHz, the two – 3dB or ‘half power’ points. Peak Sound Pressure Measurements are made using the C- frequency weighting. Measurements are primarily displayed as dB(C) or dBC. Or for example as LCeq, LCPeak, LCE – where the C shows the C-weighting.

Sound Level Measuring

A sound level meter is the device usually used to measure noise levels on the decibel scale. Several factors affect the noise level reading:
  •  The gap between the meter and the source of the sound
  •  The direction the noise source is facing, relative to the meter
  •  Noise dissipation and reverberation
In order to have the most use of the reported sound value, you need to take all of the mentioned factors in account, and state the conditions in which the reading was taken.

Final words

We hope that we managed to clarify some of the terms that you’ve been confused about or unfamiliar with.The Decibel scale is one of the most important accomplishments when it comes to sound science, and will undoubtedly be in use for decades to come.

Best Ear Plugs

The following are the best earplugs  (They go from low price to high price.)

Other Questions

What is the scale of decibels?

The human ear can pick up sounds that vary in volume from the sound of a sigh to those that are louder than a furious music festival. The decibel scale begins with zero decibels (0 dB). Someone with such a decent hearing could scarcely detect a sound at that rate. So, describing sound frequencies substantively in more understandable quantities, a logarithmic scale uses 10 as a basis instead of a linear one. This measure is called the decibel scale.

How much louder is 20 dB compared to 10 dB?

The decibel scale is logarithmic to exploit the wide variety of sounds that people can hear. On such a scale, numbers that reflect a measure or quantity are not uniformly distributed. Instead, they are increasing by multiples of a particular number. That number is 10 for the decibel scale.

20 dB of sound is ten times stronger than 10 dB of sound. The sound level in a silent bedroom, 30 dB, is 100 times greater than 10 dB. 40 dB is 1,000 times as noisy as 10 dB. Typical chat clocks are about 60 dB. A rock concert is closer to 120 dB. As per the Intensity, a rock concert is 1,000,000 times louder than a chat. This level of noise will place people at risk of hearing loss.

What is the 3dB rule?

The 3dB rule is "Every 3dB change represents a doubling or halving of sound energy."

While the human ear can differentiate between one or two pins falling, it cannot differentiate between 10,000,000,000 pins and 10,000,000,000 pins or even 10,100,000,000,000 pins since it is not a linear unit. Conversely, the important multiplication of the power of the sound can be distinguished. If you double this sound, this is equal to an increase of 3dB (decibels) using a logarithmic scale. In the sense of function, this implies that a slight increase in the number of decibels can lead to a significant improvement in the sound level, therefore, it has the ability to damage your ears.

Let's check out a couple of cases. If the sound frequency of the pin drop is 10dB, two pins will be 13dB. 10,000,000,000 pins would be 140dB and 20,000,000,000 pins would be 143dB. The 3dB rule is critical when calculating noise or assessing and predicting sensitivity for individuals.

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Last update on 2021-04-18 / Affiliate links / Images from Amazon Product Advertising API


If you require more information, please check these references

The Journal of the Acoustical Society of America , article, "asa.scitation.org", retrieved on, Tue 01-December-2020

https://psycnet.apa.org/record/1936-05651-001 , article, "psycnet.apa.org", retrieved on, Tue 01-December-2020

On the Validity of the Loudness Scale , article, "asa.scitation.org", retrieved on, Tue 01-December-2020

Author: Nick

Hi, I am Nick, and I have suffered with ear problems my whole life, mainly tinnitus. I have tried a lot of products to help protect my ears over this period, and several devices to block out the constant ringing

“Are you having problems hearing? If so, those around you already know it. Hearing loss is no laughing matter, so don’t be a punchline.”

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