Sound insulation

Introduction: Sound insulation

Often, noise control is equated with withdrawing to a quiet place or simply switching off machines and other sources of noise. In the industrial environment, this is hardly possible. The question arises then how to achieve low sound levels without affecting the function of machinery and plants, for example. After all, comfortable, quiet workplaces are a key factor contributing to the motivation of staff, as noise gets on people's nerves and makes them aggressive. This in turn can easily lead to errors in production. Subjectively, we aurally register not only different sources of loud noise but also relatively low sounds which, due to their frequency composition, can still be rather annoying.

In pertinent workplace regulations, the law requires limited noise levels at the workplace. And not without reason, since constant excessive noise exposure causes permanent hearing damage. Consequently, compliance with these regulations is monitored by the competent government safety organizations.

Noise range Noise levels in the environmentEffects on health
< 30 dB(A) Rustling of leaves, whispering, ticking of a pocket watch at a distance of 1mNone
30 - 65 dB(A) Normal conversation, background noise in the house or office, radio and television at low volumeNegative impact on the vegetative nervous system, poor concentration, poor communication
65 - 85 dB(A) Telephone ringing, loud speaking, loud machines and equipment, cars and lorries in city trafficIncreased blood pressure, increased risk of cardiovascular diseases, hearing damage after long exposure
85 - 120 dB(A) Jackhammer, motorcycle without exhaust silencer, disco music, loud walkman music, close to loudspeakers at pop concertsPain threshold, potential hearing damage even after short exposure, after longer exposure to high noise levels, permanent damage to the sensory hairs in the inner ear
> 120 dB(A) Jet planes taking off, explosions, nearby sonic boomDamage to the sensory hairs in the inner ear, damage to the nerve cells in the brain, paralysis or even death

Airborne sound absorption

Airborne sound absorption, often simply called sound absorption, is necessary when the noise level in the room containing the source of noise needs to be reduced. Airborne sound absorption is achieved by converting some of the kinetic energy of the air molecules into heat. This happens through friction on the contact surfaces of fibrous or open-pored foam materials into which sound waves can penetrate. However, other designs are also in use, such as chamber, foil and resonance absorbers. The absorption is highly dependent on frequency. Generally it is true that the lower the frequencies to be dampened, the thicker the absorption material must be. The effectiveness of sound-absorbing materials is measured, among other methods, by the degree of absorption α, the ratio of absorbed sound fraction to the incident sound intensity.

Products for airborne sound insulation


Airborne sound insulation

Airborne sound insulation, also simply called sound insulation, is required when a shield needs to be in place against sources of noise coming from other rooms, e.g. at workplaces. It is understood to be the prevention or reduction of sound penetrating through a separation plane. The sound waves are primarily reflected with the result that the sound level in the sending room increases. To counteract this effect, composites made of sound insulating and absorbing materials are often used. Sound insulation is achieved by increasing the mass per unit area, e.g. of sheet metals, using flexible insulation mats. Airborne sound insulation is dependent on frequency; the lower the frequency, the higher the mass per unit area must be. The effectiveness of airborne sound insulation is indicated by the sound insulation factor R, the difference of sound level in dB in front of and behind the separation plane.

Products for airborne sound insulation

structure borne_damping

Structure-borne sound insulation

Structure-borne sound insulation, also called anti-drumming, is used where vibrating surfaces made of sheet steel or other materials reflect airborne sound. Due to the insulation material's special elastico-viscous properties, the vibration energy is converted into heat. Sandwich structures are particularly effective but require careful planning and design. The parameter for the absorption of structure-borne sound is the loss factor d, which indicates the ability of the material concerned to absorb energy under dynamic stress (bending vibration). The loss factor is dependent on frequency and, in particular, on temperature. Therefore, it is imperative to check the temperature during continuous use before choosing the material.

Products for structure-borne sound insulation