# Decibel

Sound is all around us and can be measured to protect and inform us, as some sounds are not safe. In fact, loud noise can actually damage our hearing. So, the intensity of a sound is measured using decibel. As the human ear is incredibly sensitive, you can hear everything from your fingertip brushing lightly over your skin to a loud thunder clap. As far powe> is concerned, the sound of the thunderclap is approximately 1,000,000,000,000 times more powerful than the smallest audible sound. That makes a huge difference!

Formulas to calculate Decibel:

1. When power is given:

The most basic form for decibel calculations as given below,

$N_{dB}=10log_{10}(\frac{P2}{P1})$

1. When voltage and current are given:

$N_{dB}=20log_{10}(\frac{V2}{V1})$

$N_{dB}=20log_{10}(\frac{I2}{I1})$

Uses:

1. The decibel is mostly applied in

acoustics

as a unit of sound pressure level. In this, the reference pressure in air is set as the threshold value of perception of a human. There are many comparisons that are used to describe separate levels of pressure.

2. The decibel is used to express the ratios of power or amplitude in arithmetic ratios in electronics. The total gain of decibel can be easily calculated by adding up all the decibel gains.

Decibel Meter:

Sound can be measured with a device called as decibel meter. It measures and samples sound. Decibel meters are also known as sound-level meters. It 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.

Decibel Scale:

On the decibel scale, 0 dB is the smallest audible sound. A sound 10 times more powerful is 10 dB. A sound 100 times more powerful than near total silence is 20 dB. A sound 1,000 times more powerful than near total silence is 30 dB. A noise level chart showing examples of sounds with dB levels ranging from 0 to 120 decibels.

 Decibel Sound Source 10 Almost inaudible Normal Breathing 20 Audible Rustling Leaves, Mosquitoes 30 Very quiet Whisper 40 Quiet Stream, Refrigerator humming 50 Limited Sound Quiet office 55 Normal Sound Filtering coffee-maker 60 Fairly Quiet Normal conversation 70 Irritating Vacuum cleaner, Hairdryer 75 Constant Sound Dishwasher 80 Unpleasant City Traffic Noise 85 Loud Lawnmower 90 Extremely Unpleasant Violin 95 Noisy Farm Tractor 100 Extremely Unpleasant Train 105 Even Louder Large drum 110 Extremely Loud Symphony Orchestra 120 Extremely Loud Thunderclap, Boombox

Continue learning more about Sound and Decibel with more interesting examples and diagrams @byju’s

#### Practise This Question

The position-time graph of a body is a straight line parallel to the x axis. What does this imply?