This article was made in cooperation with Armacell.
Sounds are part of life, but there are limits to everything
Sounds enrich our life, but we would rather not hear some of them. For example, when living in an apartment building, you want privacy for yourself and your neighbors. It’s not pleasant for anyone to have the sound of every visit to the toilet or shower, every time the children play, or every relationship crisis ringing in everyone’s ears.
Whether at home or work, outdoors or indoors, the noise is almost everywhere – space is probably the only exception because the sound does not travel through a vacuum. Sound is a mechanical movement of waves that is perceived by the human auditory system as sound waves travel through the air to the ear. In addition to airborne sound, sound can also occur as vibration or frame sound, if the vibration occurs in a solid object, such as the frame of a machine or appliance.
We aim to insulate, attenuate and reject sound and noise. Each of these has its purpose:
- With sound insulation, we aim to prevent sound transmission from one space to another, either as airborne sound or through structures as structure-borne noise.
- With sound attenuation, we aim to reduce sound energy.
- With noise reduction, we aim to reduce the effects of harmful sound. In addition to sound insulation and attenuation, the aim is also to prevent sound generation.
For a person to hear a change in air pressure as sound, the frequency of the change must be sufficiently high – at least about 16 times per second. The frequency of sound is expressed in Hertz (Hz). A sound above 16 000 Hz is ultrasound and cannot be heard by humans.
Sounds from the environment are often a mixture of several sounds, and we usually perceive the combination of several sounds as noise. The unit of sound pressure is the decibel (dB), which expresses the intensity of the sound.
We reject noise in many kinds of environments
Sound insulation means reducing the power level of sound as it passes through an insulating structure such as a wall. Sound can either be absorbed into a material, pass through it, or be reflected from it.
Sound insulation is important because noise causes temporary and permanent damage to the hearing – occupational noise exposure is responsible for around 16% of hearing loss in adults worldwide. In addition, noise has negative effects on sleep and the body, for example, and makes it difficult to communicate through speech.
Noise reduction is divided into three sectors:
- General noise reduction reduces noise in the workplace.
- Environmental noise reduction aims, in particular, to combat noise caused by traffic or construction and industrial noise.
- HVAC noise engineering aims to combat noise from building services equipment and plumbing.
Without insulation, building services equipment would generate a lot of noise
Building services equipment generates noise in the home and work environment, which is why it is crucial to insulate it. You can enclose a noisy machine or appliance partially or fully. To attenuate the sound emitted from a duct, you can cover it with sound-absorbing and sound-permeable material.
Sewers are a common source of the noise. The flow of dirty water mainly generates noise through the pipe. The primary noise sources are branches and corners, where sudden flow disturbances occur.
To improve the sound attenuation of the pipe, you can choose a pipe made of sound-absorbing material or with a thicker wall, or coat the pipe with an additional lining. For example, Armacell’s ArmaComfort products are great for acoustic insulating of sewer pipes.
Let’s get quiet for a moment, but stay tuned – there’s more to come!
