Two types of instruments measure noise exposure, (1) the sound level meter, that measures the intensity of sound at a given moment and location and (2) the noise dosimeter, which stores sound level measurements and integrates them over time, providing an average noise exposure reading.
Sound level meters are more often used for area measurement, giving you the ability to map out sound levels in different areas of a workplace. Noise dosimeters provide personal exposure data, establishing how much noise a worker comes into contact with over the course of a work day. Together, these measurements can be used to establish the need for personal hearing protection equipment or an allowable amount of time a worker can be in a given area.
Both area sound level meters and personal noise dosimeters are available for rent, and where applicable, include PC software for record-keeping and compliance reporting.