1. n. [Production Logging]

A technique for recording sound at different positions in the borehole to generate a noise log. The measurement technique uses a microphone to record signals in the audible range approximately 20 to 20,000 Hz . In some circumstances, the frequency of the signal can be related to the source of noise and the flow regime, while the amplitude of the signal can be related to the flow rate. The useful signal lies approximately between 100 and 5,000 Hz, with lower frequencies generally representing background and mechanical noise. The measurement may record the total signal over all frequencies, the signal at a single frequency, or a set of measurements over different frequency ranges.

See: flowmeter,  production log