A step by step guide
Monitoring mining noise is important, but it’s not difficult. You just need to learn the different equipment and techniques that you need to be successful. If you work in mining, you know noise monitoring is critical. You must comply with regulations, and you want to get along with the neighbours. The following is an overview of how to monitor noise. It also looks at other environment factors, and what you want in a solution.
Noise is a wave caused by vibrations that make air particles oscillate. The effect is similar to that of dropping a stone into water. Sound creates ripples in the air just like the stone creates ripples in the water. The loudness, or volume, of the sound is measured in how big the ripples are. The bigger they are, the louder the sound. Volume is measured in deciBels (dB), which are technically a measure of how intense a pressure wave is relative to normal atmospheric pressure. The quietest noises we hear are 0-10 dB. Sounds of 130 dB or higher are considered painful.
Ripples in the water become smaller and eventually disappear as you get farther from where you dropped the stone. So do sound waves as you get farther from the source of the noise. This is crucial to any noise monitoring procedure, especially at a mining site. Noise regulations usually apply to areas some distance from the mine (such as a neighbouring town).
Monitoring is the best way to ensure compliance with those regulations. Here is a step-by-step look at how to monitor mining noise.
1. Place noise monitors on the boundaries of the mining area.
This will enable you to record the noise levels during mining hours. By measuring the noise levels on the boundary, you can gauge the noise levels in the neighboring communities where the restrictions apply.
2. Assess the topography and proximity to settled areas. Distances from mine to community vary widely. So do other topographical variations like hills and heavy woods. There is no set standard for how many noise monitors a given mine needs. It depends on proximity to settled areas, and to some extent on past history of complaints. In some cases, you will need several monitors for an accurate reading of the noise level in a neighbouring community. In others, one will suffice. What is constant is the need to determine on a case-by-case basis how many monitors you need.
3. Place a noise monitor at the noise source, or as close to it as possible. This allows you to compare noise levels at the source and at the boundary. You can then determine how much noise is permissible in the mine. (Failure to take this step can lead to overcorrection, or taking more precautions than are necessary, at the cost of productivity.)
4. Account for extraneous noise. Passing cars, barking dogs, noises from other industrial sites, or even a heavy wind can cause noise that you’re not responsible for. Noise monitors can’t filter out extraneous noise, but they can designate a “normal” level of ambient sound as a base level from which to measure.
5. With one noise monitor at the mining site and the other at the boundary as directed above, you can also account for extraneous noise via alert correlation. When both terminals trigger alerts, the mine manager knows the mine is responsible for the alert. When only the terminal on the boundary sounds an alert, the cause is extraneous noise.
6. Place monitors an appropriate distance from all surfaces. Generally the monitor’s microphone should be placed approximately 1.2 meters above the ground. It should also be 3.5 meters away from any other surface.
7. Directional noise monitoring is another important tool for accurate noise measurement. In mines with more than one active site, it can be difficult to assess the individual noise contributions from each source. With more than one microphone per monitor, you can account for the direction a given noise is coming from. You can also exclude noise coming from other directions, so that it is easier to assess each source individually.
Knowing how to monitor mining noise is an important part of successful mine management, but it doesn’t have to be a difficult part. With sufficient noise monitoring equipment of the right type, you can eliminate most complaints. You can also handle the ones you do receive in a timely fashion. It is not a one-size-fits-all approach, as every mine and its surroundings are different. But it is a challenge that you can always meet.