3. Definitions

Action Level: 
The level of noise exposure at which:

  • A person must be enrolled in the Hearing Conservation Program and must be provided audiometric testing.
  • Representative noise exposure monitoring is required
  • Hearing protectors and training on noise hazards must be provided to the employee.

Audiometric Testing:
Testing conducted for measuring the sensitivity of a person's hearing threshold in decibels.

Decibel (dBA):
The standard unit used to measure sound pressure level. The decibel scale is logarithmic and every five dBA is a doubling of the sound pressure level.

Hertz (Hz):
The unit of measure for noise frequency in cycles per second. (1 cycle/ second= 1Hz)

Permissible Exposure Limit (PEL):
The maximum allowable noise exposure, established by Cal/OSHA as a legal limit. The current PEL for noise is 90 dBA averaged over an eight-­hour period.

Noise Reduction Rating (NRR):
A measure of the amount of noise reduction provided by a given hearing protection device.

Standard Threshold Shift (STS):
A change in hearing threshold relative to the baseline audiogram of an average of 10 dBA or more at 2000, 3000, and 4000 Hz in either ear.