In most countries, there are regulations for the acoustical environment, which include consideration of factors such as:
- Noise transmitted from industrial buildings into the environment
- Traffic noise entering into buildings
- Noise levels inside workshops and buildings
- Noise reduction between the rooms in a building
The need for good acoustic solutions in buildings is growing rapidly with the desire to plan and build more dense areas with close connections to transport routes. The level of demand for high-class building in terms of sound insulation and room acoustics is also growing in many markets. In some cases, building regulations have already been revised, requiring better sound insulation and also room acoustics.
It is important not to confuse the terms ‘sound insulation’ and ‘sound absorption’. Sound absorbing materials, such as stone wool, will not provide much sound insulation, because it they have low mass and are permeable to air. They can help to reduce the sound level in a noisy room or increase the sound insulation in a building structure.
A special acoustic design is needed to create the suitable spaces for planned functions. There are basically two sound-related factors to be considered when designing a building:
- Choose quiet equipment (e.g. elevators, pumps, heating and ventilation equipment, etc.).
- Handle the sound in building by means of room acoustics and sound insulation.
Porous PAROC stone wool is excellent sound absorbing material
A material's sound absorbing properties are expressed by the sound absorption coefficient, α, (alpha), as a function of the frequency. Alpha (α) ranges from 0 to 1.00 (from total reflection to total absorption).
PAROC stone wool is porous. It consists of coherent material and cavities. The ability to absorb sound increases with the frequency and is also strongly connected to thickness; especially when the absorbent is placed firmly against a wall or other hard surface.
For low frequency sound, an air gap between the absorber and the reflective surface or wall will increase the sound absorption.
Picture: Sound absorption curves for PAROC stone wool at thicknesses of 30 mm (Green), 50 mm (Red) and 100 mm (blue).
PAROC stone wool is excellent material for use in sound insulation constructions
To prevent sound travelling, you have to disrupt the sound waves by:
- Filling cavities in walls so that they do not contribute to resonance
- Laying a floating floor to reduce floor impact sound
- Insulating vibrating machinery so that the vibrations are reduced
Due to the unique properties of stone wool, it is widely used in all of these applications. For example, in partitions, porous and air permeable mineral wool is the most cost-efficient sound insulation material. For the double leaf partition, it gives a 5–10 dB improvement compared to an empty wall construction.
The figure below shows the sound reduction for a double leaf wall structure with and without stone wool in the cavity.