What is dB and frequency?

dB and frequency are terms to describe sound level and the number of cycles of a sound wave in one second.

To give you a clear idea of the technical words used to describe facts about hearing impairment and noise, we have collected some key facts about dB and frequency. 

Frequency

The frequency of a sound is the number of cycles of a sound wave in one second. The unit of measurement is hertz (Hz). The frequency of a sound increases as the number of cycles per second increase. 

Vibrations between 20 and 20,000 cycles per second are interpreted as sound by a normal healthy person. A high-pitched sound could be a piccolo flute or a bird singing. Low-pitched sounds could be thunder heard from far away or tones from a bass guitar.

DeciBel (dB)

The term dB (deciBel) and the dB scale are used world-wide for the measurement of sound levels. The deciBel scale is a logarithmic scale where a doubling of sound pressure corresponds to a 6 dB increase in level. 

It is important to realize that the term 'dB' can have 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.

Here are some 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: Soft whisper
0 dB: Softest sound a person can hear

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