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Personal Sound Alarms

What are decibels?

12/01/18

Many personal safety alarms aim to disorientate attackers with sound, pungent smelling spray or red dye. Some personal attack alarms will do all three.

But how do you measure the noise levels?
And how do they compare with everyday sounds?


To measure an extremely loud and high-pitched noise we use the measure of Decibels (dB). A good personal alarm should be about 120dB or more. That's the same noise level as being at the front row of a rock concert.

But how does the sound level measure work?

The key to understanding decibel levels is to know that the increase in levels is exponential. So for every 100 times the sound volume is the decibel measure increases by a factor of 2 i.e. doubles. For example if a sound that is ten times more powerful than absolute silence is 10dB but a sound that is 100 times more powerful than absolute silence is 20dB. Therefore, a sound 1,000 times more powerful than absolute silence is 30dB.

What about real world examples of decibel levels?

Decibel Everyday Noise Levels Compared

  • 10dB Absolute silence
  • 40dB Whispering
  • 60dB Normal conversation
  • 85dB Beginning of hearing damage range, earplugs should be worn
  • 100dB Normal average car or house stereo at maximum volume
  • 120dB Front row at a rock concert
  • 130dB Marching band of 200 members
  • 140dB Threshold of pain, all frequencies
  • 145dB Vision blurs due to eyeball vibration
  • 150dB Loud rock concert, at speakers
  • 150dB Sensation of being compressed as if underwater
  • 163dB Possible glass breaking level
  • 165dB Jet airplane at take off