A free guide to measuring sounds levels in dB is now available.
It notes the main difficulty in comprehending dB measurement is its' log-linear scale. While it is useful to represent very large differences in a more user-friendly scale, it also compresses the scale. Sound is defined as any pressure variation that be be heard by the human ear. Threshold of Hearing is defined as 0 dB; the threshold for pain is around 130 dB - both readily understood, notes the guide.
However, as the power of difference between the two levels is 1013:1 or "ten million million to one," expressing it in terms becomes challenging. The guide sets sounder output levels in context with everyday examples. It also discusses the effect of frequency on perceived loudness and offers rules-of-thumb for system design and specification of warning sounders.