Everything You Need to Know about Decibel Scale

This guide contains everything you need to know about the decibel scale.

Let’s get into the article to know more!

Sound is measured in decibels. dB serves as its symbol. Decibel can be defined as

“A unit of measurement that expresses the ratio of one value of a power to another on a logarithmic scale, where the logarithmic quantity is called the power level or field level, respectively.”

Nothing compares to the human ear when considering the most amazing and adaptable sound devices.

The human ear can adjust its sensitivity to increasing sound levels and handle a wide range of sound power levels thanks to its complex internal systems and physiology.

In other words, this amazing piece of natural gear can hear a pin drop nearby and even protect itself from the roar of an engine that is close.

While some sounds might keep us safe, others might end up being harmful.

Experts utilize a nonlinear scale to conveniently express the strength of sound waves in order to help measure the various levels of sound and determine which ones are safe and dangerous. 

Decibels are the units used in this scale, which is also known as the decibel scale (dB).

In other words, a sound is louder the higher the decibel level.

sound system


How and Where Are Decibels Used?

Decibels are widely employed in acoustical and audio engineering because it’s crucial to understand how loud a sound is when determining whether a new road’s noise would be an issue or adjusting the volume of music in an arena.

The alarms from bedside monitors were making noise that patients and visitors in a multi-bed intensive care unit complained about. 

I installed sound level meters throughout the area to record noise levels [in decibels] during the day and night and used acoustic models of the space to evaluate changes within the room to better understand and attempt to eliminate these causes of complaints.

After investigation, I was able to provide a number of ideas to address the problem, each one being uniquely different due to the fact that acoustics may be impacted by almost anything.” (Rob Bungay, Acoustic Consultant, WSP)


What Is the Procedure of the Decibel Scale?

On a decibel scale, 0 dB is the lowest (quietest) sound, which is regarded as being very close to complete silence. 

According to the previously mentioned units of 10, a sound that is 10 times louder will be measured as 10 dB, a sound that is 100 times louder than 0 dB will be measured as 20 dB, a sound that is 1,000 times louder than almost silence will be measured as 30 dB, and so on.

As a result, rather than assuming a linear relationship, the human perception of sound intensity more accurately estimates the logarithm of intensity.

As a result, the decibel scale is a very useful and practical way to measure sound.


Formulas for Decibel Calculation

The calculation of decibels is possible when power, current, and voltage are provided.


  • When power is given:

The most basic formula for decibel calculations is given below:

10dB=10log10 (P2/P1)


  • When the voltage and current are given:

                                                           10dB=20log10 (V2/V1)

                                                           10dB=20log10 (I1/I2)


The Fundamental Guidelines for Using Decibels

The fundamental guidelines for using a decibel scale are listed below to help you understand how to measure sound:

Change in dB 

Change In Sound Energy 

3 dB increase The energy of sound is doubled.
3 dB decrease Sound energy is reduced to half
10 dB increase By a factor of ten, sound energy is increased.
10 dB decrease The intensity of sound is reduced by a factor of 10.
20 dB increase By a factor of 100, sound energy is increased.
20 dB decrease The power of sound is decreased by a factor of 100.


In Decibel Terms, How Loud Are Some Everyday Sounds?

Here are some common examples of everyday sounds that are measured in decibels.

  • Almost complete silence – 0 dB
  • 15 dB is a whisper.
  • 45 dB in a library
  • A typical conversation is 60 dB loud.
  • 75-85 dB of toilet flushing
  • A loud restaurant (90 dB)
  • The highest noise level in a hospital ward: is 100 dB
  • A baby wailing – 110 dB
  • Jet engine noise: 120 dB
  • The explosion of a balloon: 157 dB


How to Combine Decibels

We cannot simply add two dB measurements together because sound pressure levels in decibels (dB) employ a logarithmic scale.

For instance, if the noise level of one machine in a factory is 90 dB(A) and we start up a second machine that also measures 90 dB(A), the total noise is not 180 dB(A),

But rather 90 dB + 90 dB = 93 dB because we know that 3 dB signifies a doubling of the noise.

To combine noise levels, utilize this fast reference table too:

Comparison of two noise levels Amount to be added to the louder of the two noise levels (dB or dB(A))
0 3.0
0.1 – 0.9 2.5
1.0 – 2.4 2.0
2.4 – 4.0 1.5
4.1 – 6.0 1.0
6.1 – 10 0.5
10 0.0


  • Step 1: Determine the difference between two noise levels, then locate the matching row in the left-hand column.
  • Step 2: On the right-hand column, locate the relevant dB number.
  • Step 3: Increase the highest two-decibel measurement by the amount in the right-hand column.

Because the lower reading’s contribution to overall noise is not detected by the human ear, there is no need for an adjustment factor when the difference between two-decibel measurements is 10dB(A) or higher. 

For instance, if the noise level in your workplace is 95 dB(A) and you add another process or piece of equipment that generates 80 dB(A) of noise on its own, the noise level in your workplace will remain 95 dB(A).


Common Places Where Sound Intensity Is Measured Using the Decibel Scale


Now moving towards the common places where sound intensity is measured using the decibel scale, here are some:


1. Acoustics

In acoustics, the decibel scale is frequently used to measure the intensity of sound.

Also, the standard human sensitivity threshold is used as the reference pressure level for sound in the air.


2. Electronics

Instead of using percentages or arithmetic ratios, the decibel scale is mostly employed in electronics to indicate amplitude or power.

Moreover, the decibel scale is a helpful measurement since it makes it easy to calculate the total decibel gain from a group of components (amplifiers and attenuators).


3. Telecommunications

As sound travels from a transmitter to a receiver via a medium like free space, fiber optics, or a coaxial cable, decibels represent signal gains or losses.


4. Digital video and imaging

Decibels are typically used to express ratios of digitized brightness of video voltages when referring to digital and video image sensors.


Sound Levels for Linear and Nonlinear Decibel Scales of Intensity


Decibel Intensity Types Of Sound
130  10 Artillery fire at close proximity (threshold of pain)
120 1 Amplified rock music; near a jet engine
110 10−1 Loud orchestral music, in the audience
100 10−2 Electric saw
90 10−3 Bus or truck interior
80 10−4 Automobile interior
70 10−5 Street noise; loud telephone bell
60 10−6 Normal conversation; business office
50 10−7 Restaurant; personal office
40 10−8 Silent room in the home
30 10−9 Quiet lecture hall; bedroom
20 10−10 Radio, television, or recording studio
10 10−11 Soundproof room


Although the decibel scale is nonlinear, it may still be measured directly with sound level meters.

Moreover, decibels are most frequently used when measuring sound levels for audio systems, architectural acoustics, and other industrial applications.


Applications of Decibel Meter or Decibel Scale

Acoustic measurements are performed using a decibel meter.

However, acoustic sound propagation is the movement of sound through the atmosphere.

Moreover, this tool typically consists of a small microphone-equipped device that measures noise.

A diaphragm is a transducer used in acoustics to turn mechanical vibrations into sounds or the other way around.

The microphone’s diaphragm responds to variations in air pressure brought on by sound waves.  

  1. This is another reason why this instrument is also called a Sound Pressure Level (SPL meter).
  2. However, the sound pressure variation is translated into an electrical signal during diaphragm movement (V).
  3. A microphone can be identified by the voltage generated when constant pressure is applied; this voltage is referred to as microphone sensitivity.

The decibel meter properly translates the electrical signal to sound pressure using the microphone’s sensitivity and displays the resulting level of sound pressure (decibels dB).

  1. This device functions as a level meter and is typically used to measure noise. However, short-term exposure to loud noises doesn’t affect people significantly, but repeated exposure can lead to bodily harm, such as damage to the eardrums.
  2. In research on noise pollution, sound level meters are primarily used to quantify the various types of noise. In order to effectively take action to lessen the sound, this instrument aids in measuring the sound’s strength by measuring its decibel level.



Through this article, you are able to know about the facts of the decibel meter.

Moreover, you are able to learn about the formulas of decibel meters, fundamental guidelines for using this meter, and about the common places where sound intensity is measured using a decibel scale.

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