Ambient noise is what operators regularly hear inside a mobile equipment cab or cabin. Without enough acoustic insulation, this background noise can exceed allowable decibel (dB) limits for human health and safety. Ambient noise can also make it harder for workers to hear radio communications or audio alerts. In addition, sound-induced vibrations can cause fasteners to loosen or induce metal fatigue.

To reduce ambient noise in mobile equipment cabins, follow this three-step process from Elasto Proxy.

  1. Find the source of the sound
  2. Isolate the noise from the listener
  3. Modify surfaces and provide an escape

Elasto Proxy makes sound absorbers, sound blockers, and sound dampeners for both on-road and off-road equipment. We also fabricate custom “insulation sandwiches” that use different materials in special combinations. Contact us to discuss your noise control application.

#1 Find the Source of the Sound for the Ambient Noise

Finding the source of the source of the sound is the first step in reducing ambient noise. Sometimes, an operator will blame the rattle of a window when vibrations from the chassis are to blame. Until your engineering team determines the path of the sound, you might think you need new locking gaskets instead of more vibration mounts.

#2 Isolate the Ambient Noise from the Listener

The second step in noise reduction, isolating the generator from the listener, involves a series of tasks.

  • Plug the holes
  • Reduce the vibrations
  • Determine the frequency
  • Isolate the engine from the frame

Plug the holes. Because sound travels through air, you need to plug any holes inside the cab or cabin. Often, these gaps are located near the steering column, pedals, or stick shift. You can plug holes with acoustical foams that you cut by hand, but manual cutting is imprecise. For better noise control, order water jet cut parts from Elasto Proxy. They fit snugly around cabin feature and eliminate air gaps.   

Reduce the vibrations. Sound-induced vibrations can transform a mobile equipment cabin into a resonance box. By installing a sound absorbing foam inside the cabin, you can absorb or block these vibrations. Installing a dense elastomeric barrier inside the engine casing can also help. This sound barrier makes it harder for the engine to transmit vibrations to the cabin’s frames and walls in the first place.   

Determine the frequency. Sound is like an ocean wave. Low frequency sounds are like massive waves that are relatively far apart but powerful enough to erode the coast. High frequency waves have shorter peaks and hit the beach in rapid succession. In mobile equipment, the noise from a diesel engine is a low-frequency sound that is difficult but not impossible to stop. Ask Elasto Proxy for assistance.   

Isolate the engine from the frame. Engines that have greater contact with a frame or chassis transmit greater amounts of vibrations. To isolate the engine from the frame, add flexible joints or install additional vibration mounts. Elasto Proxy can source these rubber-to-metal bonded assemblies for you and ship them along with custom acoustic insulation such as headliners and floor mats.

#3 Modify Surfaces and Provide an Escape

To reduce decibel levels significantly, you may need to do more than add acoustic insulation. Creating non-parallel surfaces for both the engine casing and the cabin can help. It is also important to provide an angle of escape for reflected energy. For example, you can angle the inside of the engine toward the road to provide an escape path. Otherwise, the sound may reflect off the opposite wall.

Nine Ambient Noise Control Solutions

Do you need acoustic insulation for forestry, mining, construction, or other types of heavy equipment? The Elasto Bag, a sack full of samples from Elasto Proxy, contains nine noise control solutions (such as for sound absorption) that you can see for yourself and hold in your hands. If you are a mobile equipment manufacturer, we invite you to ask for the Elasto Bag.

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