Sound, a remarkable fact

Even electrical machines can be harmful

Construction machinery produces noise. They often largely determine the noise impact on users and surroundings. This is why guidelines have been established for machines regarding noise production, the guaranteed sound power level. Aboma Inspections is the only government-appointed body in the Netherlands authorized to perform these noise measurements and points out that noise is a curious thing. A machine that is fine to the ear, for example an electrical piece of equipment, does not by definition have to produce less sound pressure and can still be harmful to user and environment.

When placing a construction machine on the market, the manufacturer is obliged to have the guaranteed sound power level measured, begins Bas van Gruijthuijsen, general manager Aboma Inspections. "At our location at the construction and infrastructure park in Harderwijk, we have all the equipment and facilities to measure the sound power level according to the latest guidelines. We do this with some regularity for many a manufacturer and occasionally for a user. Because even if you import a machine from outside the European Union, for example, you must comply with the directive. And the same goes for converting a machine from fossil to electric."

Sniper

A big misunderstanding, according to Rudo Smits, coordinator of noise measurements within Aboma Inspections, is that electric equipment is quiet. "When we start measuring, the guaranteed sound power level is not necessarily much lower than a comparable diesel-powered unit. The high and low tones can be just as damaging. Even though as a person you don't perceive them as well. It is also called the silent killer. That realization is sometimes lacking even among manufacturers, so it's a good thing that laws and regulations put a stop to it." Van Gruijthuijsen adds: "The guaranteed sound power level not only relates to the person operating the machine, but also says something about the people in the immediate vicinity of the machine. Measurements are therefore carried out at several positions simultaneously in a radius of 4, 10 or 16 meters around the machine."

Adjusted guidelines

Basically, measurements are always taken in a hemispherical shape around the machine. Since last May 22, the guidelines have been updated, which has changed the measurement requirements. For quieter machines, a rectangle arrangement can also be used for the microphone positions. Smits: "The noise level of, for example, generators and water pumps is measured in a rectangle arrangement at a distance of 1 meter from the machine. The results of each measurement are processed and we publish them in a report. Based on the results of the measurements and the measurement uncertainties, we issue a certificate of the guaranteed sound power level, provided the machine complies with all guidelines. Machine manufacturers have an obligation to verify that their machine complies. Any changes to the machine, such as choosing a different fan or speed, can also affect the guaranteed sound power level."