317-774-1900What is a Decibel?
A decibel is used to express the sound intensity level. It is commonly abbreviated as dBA.
The decibel scale is logarithmic, so each 10 decibel increase or decrease is an order of magnitude louder or softer. The table below shows how much the human ear can perceive a change in decibel.
| Change in level (dBA) | Human perception |
| 1 | Imperceptible |
| 3 | Barely perceptible |
| 5 | Clearly noticeable |
| 10 | Substantial change |
The table below shows decibel levels of some common industrial activities.
Decibel Scales
With a handheld sound level meter, or even smartphone app, sound levels are measured according to three different weighing networks: A, B, and C. We will not discuss the B and C scales here. The A scale, expressed as dBA, is used for all regulatory measurements from OSHA and EPA. This is because the response characteristics of the human ear and the incidence of noise-induced hearing loss closely matches the A scale.