The Mayor's Ambient Noise Strategy - Greater London Authority

262 Mayor of London
The Mayor’s Ambient Noise Strategy
Sound power The total sound energy radiated by a source per second.
Sound Pressure Level The amplititude of the changes in pressure level
of a sound wave, measured in either pressure units (Pa) or using the
decibel logarithmic reference scale.
Sound quality Not just the overall sound level, but the mix of sound
frequencies and other characteristics of sound through time, which may
be appraised using a range of terms such as ‘roughness’. Can include
issues of meaning, context, and other qualitative aspects.
Soundscape The overall quality of an acoustic environment as a place for
human experience. Soundscape design may encompass reduction or
elimination of certain sounds (‘noise abatement’), preservation of certain
sounds (‘soundmarks’), and the combination and balancing of sounds to
create or enhance an attractive and stimulating acoustic environment
(analogous to the sound engineering of products). A ‘soundwalk’ is a
walk, often guided, designed to enhance awareness of the richness of the
sound world.
Standardised mode or standard mode In the context of aircraft noise
contours for Heathrow, the use of a 20 year rolling average for the
percentages of easterly and westerly movements, used to distinguish year
on year change due to changes in aircraft noise from those which may be
due to changes in the balance between easterly and westerly operations.
Statutory nuisance Under the Environmental Protection Act 1990,
‘noise emitted from premises so as to be prejudicial to health or a
nuisance’ may constitute a statutory nuisance.
Strategic referrals planning applications of potential strategic
importance referred to the Mayor under the Town and Country Planning
(Mayor of London) Order 2000 (Statutory Instrument No 1493).
Street canyon a street contained by buildings which are tall relative to
the street width, and which line up continuously on both sides (see
Nicholson SE. ‘A pollution model for street level air’ Atmospheric
Environment 9, 1975, pp 19-33). Continuous façades, or fairly continuous
building frontages with small gaps between buildings can screen noise
from areas to the rear. However, multiple reflection of sound between
façades facing the street can increase noise levels. Designers should
consider the need for acoustically absorptive façades, including deep,
acoustic profiling, as well as absorptive panels. Very deep and long