4. Unwanted noise can have a significant impact upon environmental quality, public health and amenity. It is important to be aware of the sources of noise in the environment in order to minimise or prevent its effects. Common sources of noise include road vehicles, aircraft, railways, industry, landfill operations, construction, commercial premises and entertainment venues, and sport and recreation venues. The Environmental Noise Directive ( END) describes environmental noise as " unwanted or harmful outdoor sound created by public activities, including noise emitted by means of transport, road traffic, rail traffic, air traffic, and from sites of industrial activity" (Directive 2002/49/EC, article 3). It focuses on the impact of such noise on individuals and serves to prevent noise levels that would endanger the health and quality of life of any person. END does not apply to noise that is caused by the person exposed to the noise, noise from domestic activities, workplace noise or noise inside means of transport or due to military activities in military areas.
5. Noise is measured in decibels (dB), where zero dB is the lower limit of audibility and 140 dB is the level at which physical pain in the ear may be felt. Individual sensitivity to noise is highly subjective and is affected by a range of factors. As these can include non-acoustic matters, such as attitude to the noise source, sensitivity may not always relate directly to the level of noise.
- Decibel (dB): a unit derived from the logarithm of the ratio between the value of a quantity and a reference value. It is used to describe the level of many different quantities, including noise.
- dB(A): decibels measured on a sound level meter incorporating a frequency weighting (A weighting) which differentiates between sounds of different frequency (pitch) in a similar way to the human ear. Measurements in dB(A) broadly agree with people's assessment of loudness. For noise of a similar character, a change of 3 dB(A) is the minimum perceptible under normal conditions, and a change of 10 dB(A) corresponds roughly to halving or doubling the loudness of a sound.
6. Some common sounds and their decibel ratings at source are:
- Unsilenced pneumatic drill (at 7m distance) - 95dB(A)
- Heavy diesel lorry (40km/h at 7m distance) - 83dB(A)
- Modern twin-engine jet (at take-off at 152m distance) - 81dB(A)
- Passenger car (60 km/h at 7m distance) - 70dB(A)
- Office environment - 60dB(A)
- Ordinary conversation - 50dB(A)
- Quiet bedroom - 35dB(A)