DeciBel (dB)
The term dB (deciBel) and the dB scale is used all over the world for the measurement of sound levels. The deciBel scale is a logarithmic scale where a doubling of sound pressure corresponds to a 3 dB increase in level.
It is very important to realize that the term 'dB' has different meanings and is not a fixed value like the volt or the meter etc. The value of a dB depends on the context in which it is used.
Very often, sound pressure is expressed either in dB SPL, where the weakest sound detected by a normal hearing person is 1000 Hz or in dB HL which corresponds to the normal hearing threshold of a specific sound, (e.g. from 125 Hz to 8000 Hz), 0 dB SPL and 0 dB HL are therefore not the same.
It is very important to realize that the term 'dB' has different meanings and is not a fixed value like the volt or the meter etc. The value of a dB depends on the context in which it is used.
Very often, sound pressure is expressed either in dB SPL, where the weakest sound detected by a normal hearing person is 1000 Hz or in dB HL which corresponds to the normal hearing threshold of a specific sound, (e.g. from 125 Hz to 8000 Hz), 0 dB SPL and 0 dB HL are therefore not the same.
Examples of different sound intensities as expressed in dB(HL):
- 180 dB: Rocket at take-off
- 140 dB: Jet engine at take-off
- 120 dB: Rock band
- 110 dB: Loud thunder
- 90 dB: City traffic
- 80 dB: Loud radio
- 60 dB: Ordinary conversation
- 30 dB: Very soft whisper
- 0 dB: Softest sound a person can hear
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