Rationale for the use of Paired Continuous Real Time Noise Monitors to Reduce Uncertainty in the Quantification of Noise from Open Cut Coal Mines

Numerous experimental studies of varying duration have been undertaken by researchers to investigate the propagation of sound over a range of distances. These studies demonstrate there is significant variability in the propagation of the measured sound to far-field locations when correlated with prevailing meteorological conditions. This variability leads to a large range of plausible noise level outcomes when considering a specific meteorological condition.

This variability in the measured versus expected outcome has led to uncertainty in the management of noise compliance, which has been addressed by many mines installing real time noise monitors to measure the far-field noise levels emitted from their respective mining operations.

The objective of this project was to investigate the use of paired noise monitor systems to reduce uncertainty in the quantification of noise from open cut coal mining operations.

The experimental study confirmed the high variability in the measured noise levels at far-field locations when correlated with the prevailing meteorological conditions, demonstrating that the conventional meteorological descriptors available to the mining operations can be an inconsistent predictor of elevated noise levels.

The research demonstrates how a far-field monitor with directional capabilities offers a greater degree of certainty in the quantification of source contribution than an omni-directional monitor.

The simple addition of a near-field monitor by itself does not automatically improve the confidence in the decision making that would be obtained from a directional far-field monitor. However, in the right circumstances, the near-field monitor is crucial as a measurement surrogate (or proxy) for the dynamic intensity of the mining activity. This enables the evaluation of the sound propagation relationship between the mine and the far-field monitoring location.

Paired noise monitors coupled with a description of the prevailing meteorological conditions can reduce the uncertainty in the quantification of source contribution at the far-field noise monitor, by narrowing the range of plausible outcomes as compared to conventional approaches. This would result in increased confidence in the source contribution analysis and the subsequent decision-making process. The outcome for the mining operation would be a reduction in production losses due to false-positive events and an improvement in environmental compliance.