Sound Attenuation

Sound attenuation is useful and often needed within the diesel industry. Large mechanical workings, namely generators, need a soundproofing mechanism to protect both the hearing and mental peace of those around. It is important that we understand what exactly sound attenuation is and why it is so important. Let’s take a quick walk through the basics of sound reduction.

Sound attenuation is similar to soundproof or noise reduction. It means to reduce or thin a particular sound. How does something thin or reduce sound? The factor for reducing a particular sound depends on where the sound is coming from. If it is airborne, it originates from the outside.  To keep a particular sound out, it is important to insulate the space. If the sound is generated inside a room, the sound is being absorbed.  And if it a sound is transmitted throughout a structure,  the structure should be isolated from the particular source of sound vibration.  Porous and cellular materials which are solid can be good at absorbing energy which allows them to help isolation. However, they are not good at insulating against sound.

sound attenuation

Sound Absorption

Sound absorption is where a sound wave is not reflected nor is it transmitted. The energy of the sound vibration are absorbed into and permeate the material. Three categories of sound absorbers are as follows:There are three basic categories of

  • Porous materials usually

Made out of spun or matted or fibres. Common porous absorbers include draperies, fibrous minerals wool and glass fibres, carpets, spray-applied cellulose, and open-cell foam plaster. Air flow is allowed which converts the sound energy into heat.

  • Panel (membrane) absorbers having an inflexible

surface mounted over an airspace. Think of it like a tight lid.  Common panel (membrane) absorbers include lightweight impervious ceilings and floors, thin wood panelling over framing, and glazing.

  • And resonators created by slots connected

to an enclosed chamber of trapped air. The best and most widely used example of a resonator is the renowned Helmholtz resonator. The size of the opening on this bottle shape, the length of the bottleneck, and the amount of air trapped in the air chamber account for the resonation.

Isolation

Elastic materials and steel frames can allow vibrations to travel through a building.

This type of noise is travels through continuous solid connections. Adding in a float or air chamber in the floor can muffle or reduce the sound. You can also put the building on resilient material or ue cellular materials.Putting the whole structure on resilient

pads can also isolate buildings.

Insulation

Foams are not good at sound insulation. Sound insulation requires a heavier mass than that of heat insulation. Add concrete or brick layers to a wall or floor will do much better at improving sound reduction.

A basic generator enclosure is constructed with metal panels that are riveted, bolted, or screwed together to create a complete enclosure. There is also a welded option where the framework of metal elements that have been fabricated or are structural is covered with sheet metal and attached with welds, rivets, bolts or screws. Some structures use panels that come pre-manufactured and are connected to form side and roof panels. Usually it comes with a Pre-hung door, and the wall and roof panels generally include either acoustic or thermal  insulation, while a sheet of metal lines the interior genset. The stressed skin construction method is where fabricated shapes are connected together to form a general structure. Then it is integrated with an external skin and finally connected together with hard rivets. Stressed skin produces a lightweight but durable enclosure where the skin as well as the structural lining combine and become load-bearing components.

Each type of enclosure offers varying levels of sound attenuation, and costs varying amounts based on materials and level of sound attenuation. Keeping in mind the basics of sound theory and ways to mute or thin sound, you can create a peaceful and healthy working/living environment.