How are jet aircraft cabins soundproofed

Modern foams for sound insulation

When a sound wave hits a porous, soft and deformable surface such as foam, the foam absorbs the sound almost completely. From a physical point of view, it involves the conversion of kinetic energy - in the form of the airborne sound wave - into heat. The degree of absorption, i.e. how far the foam attenuates the sound wave, depends on the thickness and density of the foam and the sound frequency of the sound wave. The following applies: A thicker foam has a much better sound-absorbing effect at a higher sound frequency.

For sound insulation, convoluted foam in particular is an excellent material that is also very inexpensive. This foam is suitable for soundproofing factory halls, call centers, open-plan offices, living rooms, music and rehearsal rooms or for lining motor housings. But textiles can also improve room acoustics, as reported by www.architekturzeitung.com. They reduce reverberation and noise levels in the room in which they are installed.

Areas of application for acoustic foams

There are more and more sources of noise in the environment. It could be the neighbors or the discotheque in the neighborhood, the street noise or loud machines. Good sound insulation is used so that the noise does not become a nuisance. Profiled acoustic foams, such as knobbed and pyramid foam, are very suitable for sound absorption. A comprehensive foam overview is available e.g. at www.schaumstofflager.de.

Types of acoustic foams
Light foamsReverb reduction
Convoluted foamAttenuates medium and high frequencies
Planner foamReduce noise and reverberation
Pyramid foamAttenuation in the medium and high frequency range
Acoustic foam made from Basotectfor sound absorption and reverberation reduction
Heavy foamsfor sound insulation
Composite foamsfor sound and noise insulation
Bitumen foil and bitumen cardboardfor sound deadening of metal parts, e.g. in motor vehicles

When a sound wave hits a porous, soft and deformable surface such as foam, the foam absorbs the sound almost completely. From a physical point of view, it involves the conversion of kinetic energy - in the form of the airborne sound wave - into heat. The degree of absorption, i.e. how far the foam attenuates the sound wave, depends on the thickness and density of the foam and the sound frequency of the sound wave. The following applies: a thicker foam has a much better sound-absorbing effect at a higher sound frequency.

For sound insulation, convoluted foam in particular is an excellent material that is also very inexpensive. This foam is suitable for soundproofing factory halls, call centers, open-plan offices, living rooms, music and rehearsal rooms or for lining motor housings. But textiles can also improve room acoustics, as reported by www.architekturzeitung.com. They reduce reverberation and noise levels in the room in which they are installed.

Soundproofing and soundproofing - what's the difference?

Sound attenuation and soundproofing are often used interchangeably, but they refer to two different things.

Sound attenuation or sound absorption means the absorption of airborne sound, for example by open-pored materials. The sound hits the material and is converted into heat that cannot be felt by humans; the amount of energy is too small for that. The corresponding foams consequently prevent the sound from spreading further. Foams that have a very large internal surface are particularly suitable. The surface is enlarged by the pores. Good sound insulation improves the acoustics in the room because it reduces the reverberation caused by sound reflection from the walls. The thickness of the foam varies depending on the frequency. Very thick panels can also absorb low frequencies.

Sound absorption is about the room acoustics and the reflections of the sound by airborne sound. Knob and pyramid foams or molded foam parts are particularly suitable here.

Sound insulation, on the other hand, prevents sound from spreading into adjacent rooms or houses. It is important in building acoustics. Airborne noise and converted structure-borne noise are to be prevented from spreading. Here, noise insulation panels are usually used in conjunction with bitumen panels or heavy foil, such as heavy composite foams or flat foams.

How is sound created and how does it penetrate walls?

Sound waves move through the air, creating airborne sound. As soon as this airborne sound hits an ear, humans and animals can perceive this sound as a noise. The following applies: the greater the sound pressure generated, the louder the resulting noise. People find high sound pressure levels uncomfortable. A sound wave is nothing more than a change in the air pressure that is spreading. People need sound to be able to communicate using language. Sound waves propagate at a certain speed and in all directions. In air they propagate at the speed of sound. When airborne sound hits objects, it is transformed into structure-borne sound at the boundary between air and surface. The body begins to vibrate. Depending on how large the energy content or the sound pressure is, the sound penetrates the objects more heavily or more easily. On the other side of the object, the structure-borne sound is converted back into air-borne sound. How strong the effect of structure-borne noise is also depends on the mass and inertia of the object.

Sound insulation to the neighbors

The problem is widespread that the noise produced from outside, for example from neighbors or street noise, is a nuisance. Effective sound insulation can be achieved with special insulation sets that can be screwed to walls and ceilings. Vibrations are no longer transmitted, silence arises.

Soundproofing machines

Large machines and heavy equipment can be a tremendous noise nuisance. To make these devices quieter, they can be insulated from the inside, for example, provided there is enough space. Another possibility is to build a frame around the device in question and to insulate it with foam.

How much soundproofing is possible?

How many dB wall insulation reduces the noise cannot be said in advance, as this depends on various factors. The thicker the insulation boards, the more they can insulate. Even small changes to the dB number can have a pleasant effect. Noise insulation is important when it is too loud because noise can make you sick. At www.laermschutz.nrw.de there is a brochure with tips on how to reduce noise effectively. Here are some examples of how loud the environment is:

Source of noiseMeasured dB number
A quiet room20 to 30 dB
A normal loud conversation40 to 60 dB
Room loud TV60 dB
Car engine60 to 80 dB
Main thoroughfare80 to 90 dB
Jackhammer or discotheque100 dB
Jet110 to 120 dB
Hearing damage with only short-term exposureMore than 120 dB

This is how sound insulation works

Solid foams are best for effective soundproofing. These are of course heavier than, for example, pure acoustic foams, which only reduce the reverberation and noise in a room. The installation of sound insulation is therefore a little more complex. In most cases, the foam panels can be glued over the entire surface with a special assembly adhesive. In the case of particularly heavy panels, mechanical fixation can also be helpful. For example, wooden struts or grids that support the foam are suitable.