Intensity level is one of the two main sound features utilised in the normal detection of sound. It is measured in decibels (dB).
	A low dB value corresponds to a softer sound, while a high dB value corresponds to a louder sound. The decibel is a ratio of a given intensity level to a reference intensity level.

Note :
There are different types of dB, based on the reference level used, an additional abbreviation will define the specific type:

• dB HL
  • HL means Hearing Level
  • indicates a person's hearing relative to the average threshold values across frequency for normal hearing
• dB SPL
  • SPL means Sound Pressure Level : indicates the sound pressure

Normal hearing persons can detect very soft sounds of 20 dB to very loud sounds of 120 dB. Above this level the sounds typically become uncomfortable.