What is decibel (dB) in Audio

decibel scale

Decibel (dB) is a ratio that allows us to compare two audio levels in same manner in any media.

Decibel can be used for any medium used for sound propagation. Some of the mediums are listed below.

  • Sound travel through Air
  • Sound as Electric Signal
  • Sound as Magnetic Signal
  • Sound as Digital Signal
  • Optical Signal on a Film Sound Track
  • Mechanical Signal on a Vinyl Record
SoundTrack on Optical Film

A change in level of 3dB means the same thing in any media.

The ear recognises sound levels logarithmically rather than linearly. So a change of 100 ┬ÁN/m2 will feel much louder if the start point were quiet. But the same will feel small change, if the start point were already loud previously.
So a change of 3dB will create same degree of impact whatever the start point will be.

decibel formula

P1 = Sound Pressure of Audio Level 1
P2 = Sound Pressure of Audio Level 2

decibel = 20 x log10 (P1 /P2 )

  • -80 dB = 1/10000 times
  • -60 dB = 1/1000 times
  • -40 dB = 1/100 times
  • -20 dB = 1/10 times
  • -12 dB = 1/4 times
  • -6 dB = 1/2 times
  • 0 dB = No Change
  • 6 dB = 2 times
  • 12 dB = 4 times
  • 20 dB = 10 times
  • 40 dB = 100 times
  • 60 dB = 1000 times
  • 80 dB = 10000 times

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