The first step toward solving any noise problem is to define it. To understand what requirements must be implemented according to OSHA’s noise standard [29 CFR 1910.95, it is necessary to determine exposure levels. The following sections provide information about evaluating noise exposure levels:

Indications of a Problem
Walkaround Survey
Workshift Sampling
Instruments Used to Conduct a Noise Survey (App III:A)

Follow the link to OSHA site:  How do I evaluate noise exposure

Workplace INTEGRA, can be a resource for your sampling needs:  Noise Surveys and Dosimetry Studies