Industrial Applications

Industrial environments such as printing houses, bottling plants and mail sorting rooms are usually typified by constant noise that creates a painful din. This not only wears on the employees, but by the end of the day, studies have shown that this negatively affects productivity.

When the noise levels are extreme, preventative measures are enacted to ensure employees are protected from prolonged exposure. These measures are generally mandated by government agencies such as OSHA in the United States and CCOHS in Canada. Remedies such as wearing protective hearing are sometimes suggested, but this introduces a new problem: safety. Without proper means of communication between employees, the likelihood of accidents increases as there is no way to shout at someone and have them move out of the way should a dangerous situation present itself.

With this knowledge, more companies are introducing acoustic treatment as a means to reduce ambient noise for greater employee productivity, while reducing exposure to excessive sound pressure levels. This not only shows employees that management cares; the company saves in the long run by reducing health costs and lowering accidents. Employee retention increases along with job satisfaction.

Acoustic treatment

Think of firing up your lawnmower in your garage. What happens? It becomes unbearably loud as the engine roars, quickly overwhelming the room's ability to cope. Go outside, and the noise seems to be much less irritating. But if the engine is just as loud as before, what happened? Simply put, you have eliminated the reflective boundaries. The sound is being absorbed by ‘open space' instead of reflecting back at you. A music practice room behaves exactly the same way. Left unchecked, the sound in the room will exceed the room's ability to absorb it and the energy quickly overwhelms the space. It becomes loud and uncomfortable.

The solution is easy: Treat the wall surfaces with absorptive acoustic panels. These effectively absorb sound energy in the room and make it a more comfortable place to work. Because there is less energy left in the room to resonate, the walls do not have to work quite as hard.

Selecting the right acoustic panel for the task begins by considering what frequencies you are attempting to control. A major error that many studios make is that they will install some low-density foam that will have no effect on the problem frequencies.

Panel placement

Mounting absorptive panels on the walls is usually the first plan of action when it comes to attenuating excessive sound in industrial plants. These are generally easy to install and very effective. The acoustician will generally begin by treating corners as this is where you enjoy maximum benefit. Sound energy from the shop floor tends to beam and reflect off hard surfaces. By positioning the panel in the corner, you not only absorb the sound that hits the panel, you also trap the sound as it reflects off the ceiling, doubling the performance without any added cost.

As the room gets larger, corners are ‘created' using sound baffles. These hanging panels look like flags or banners and are usually distributed high up in the rafters in a crisscross pattern. This approach brings the panels closer to the source and of course captures the sound as it reflects off the ceiling sooner. The result of course in less reverberation and echo in the room.

Although there are no hard rules of thumb, industrial installations are commonly treated with 10% to 15% of the wall space. This of course will depend on the sound levels and the quality of the panel being used.

Controlling high sound level devices

When confronted with a machine that is particularly loud, an effective solution is to create a canopy and treat the inside surfaces with high performance acoustical panels. Depending on the offending frequencies, this will usually be 1-, 2- or 3-inch thick Broadway panels. The following design is particularly effective as it helps prevent flanking.

The canopy is usually suspended above the machine to allow full access for employees. In some cases, this will be augmented with a gobo wall or ‘go between' which will serve to obstruct the direct path of the sound.

Compressors and engine rooms

If you have an equipment room that is so loud that the walls do not contain the offending noise, there are several remedies. The first is treating the inside of the room with Broadway acoustic panels. By reducing the energy inside the room, the walls do not have to work as hard as the absorptive panels will reduce the noise within which means there is less noise to escape.

The next step involves increasing the mass of the walls, ceiling and doors. Greater mass means that it will require more energy to cause the walls to vibrate and pass sound.

For the walls and ceiling, adding mass is easily accomplished by adding a second or third layer of gypsum board. For extremely noisy rooms, firing out the wall by introducing an air space in between the original wall and a new layer of gypsum board will deliver even greater benefit as this causes a ‘spring-like' or ‘shock absorber' effect whereby each wall will now vibrate independently. A common product known as resilient channel is produced for this purpose. You can further improve the wall performance by introducing a different mass to each side of the ‘spring' by varying the thickness of the gypsum board. For instance by using two pieces of ½” (1.25cm) thick gypsum for one layer and two thicker pieces for the other., This way, when the inner gypsum layer is set into vibration, it will not sympathetically vibrate like a drum skin with the pouter layer.

Doors tend to also pose problems: If the door is made with a light-weight hollow core, this should be replaced with a heavy solid core type. Sealing the door with weather stripping all the way around will also help.

Summary

Controlling the acoustics in industrial spaces is simply a matter of getting treatment up on the walls and distributing it around the room. Broadway panels deliver effective absorption through the critical communication range. By reducing noise in the workspace, you not only make the place more comfortable, you also decrease the potential for accidents, reduce work stress and gain with greater employee satisfaction. This shows management cares and results in greater staff retention.

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Determining Coverage

To determine the coverage, we have created a series of easy-to-use tables that enable you to choose between various degrees of treatment depending on your budget and the desired outcome. Most facilities find that a ‘light’ level of treatment provides sufficient sound abatement while keeping the budget in check. If budgets are tight, start with minimal treatment and then add more panels as funds become available.