Noise is a familiar form of pollution that affects us all. But it’s unlike other forms of pollution, because once the noise stops, the pollution immediately comes to an end and the environment is free of it. Other forms of pollution such as sewerage and chemicals can be difficult to remove from the water, soil and air environment.
The perception of noise is always a difficult subject. For some, the sound of a Grand Prix race is thrilling and gives enjoyment to many, whereas to others it is annoying and constitutes a noise nuisance. The same is typical of loud music. Many younger people enjoy listening to music set at high volumes while it infuriates others. So noise is subjective, in some ways it is enjoyed by some but for others, is an unwelcome form of noise pollution such as listening to your neighbour’s television when you are trying to quietly read a book.
It is now well known that excessive noise is a danger to health and can cause stress, sleeplessness, annoyance and many other uncomfortable symptoms.
A rough guide to how noise is measured is shown in the table below.
|80dB||Inside a sports car|
|90dB||Road drill at 3 metres|
|140dB||Threshold of pain|
As you can see from the table, anything over 80-85 dB in volume is very uncomfortable and can impair hearing. Lower volumes of noise can also be annoying if it is disturbing, particularly at night. Normally there are two ways to reduce noise nuisance. One is to eliminate the noise at source, giving instant relief or if this is not possible, introduce soundproofing to reduce the noise nuisance.
Sound travels as spherical ripples through the air much like the ripples created on a pond after a stone has been thrown in. As the ripples travel further away from their source, they reduce in intensity and if they hit a solid barrier or hit reeds, their energy is split up and dissipated in much the same way as sound absorbing materials work.
This is noise that is as the title suggests, airborne and is the type of noise created by speech and radio. Airborne noise tends to be the most annoying when noise is proving to be a nuisance.
Impact noise again is as the title suggests and is generated by items coming together such as a door slamming or footsteps over a hard floor. Installation of hard floors in flats is a widespread reason for noise nuisance to neighbours living below flats that have this type of floor installed.
Flanking noise is more often perceived in flats where noise is transmitted through the fabric of the building. Flanking noise is more often caused by impact noise and often travels through the walls of the building.
This is more of a problem if the walls are of a lightweight construction so it is important the correct density blocks are used in the construction of new flats today.
Normally a minimum 7 kilonewton density block is specified today to reduce flanking noise nuisance and also help comply with the current regulations for noise control in flats and other multi-occupied buildings.
Noise from vibration is often a problem and can be caused by something simple such as a washing machine or a more extreme example such as heavy industrial machinery in a factory. Noise from vibration will generate both flanking noise and airborne noise depending on its location.