The Portable Acoustic Monitoring Package (PAMP) has been designed to record and monitor the acoustic signal in natural gas transmission lines. In particular the three acoustic signals associated with a line leak. The system is portable ((approx.) 30 lbs) and is designed for line pressures up to 1000 psi. It has become apparent that cataloging of the various background acoustic signals in natural gas transmission line is very important if a system to identify leak signals is to be developed. The low-pressure (0-200 psig) laboratory test phase has been completed and a number of field trials have been conducted.