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Glossary

Glossary of acoustic technical terms


Acoustic Environment (or Specific Noise Situation)

Noise from all noise sources as modified by the environment.

Acoustic Evaluation

Verification of conformity with lthe egal requirements of specific noise situations.

Adaptation Term (C or Ctr)

Correction defined in EN ISO 717 -1, function of the spectral characteristics of the noise at source, to annex to the airborne sound insulation index.

Ambient Noise

Totally encompassing noise in a given situation at a given time, usually composed of noise from many sources near and far.

Classification of Acoustic Zones

The delimitation and organozation of sensitive areas and mixed areas is an errand of the Local Authorities, in terms of spatial planning for Local Plans.

Consolidated Urban Zone

Sensitive or mixed zone with stable occupation in terms of the built environment.

Measurement Time Interval

Time interval of each measurement within the observation period.

Mixed Zone

Area defined in the Boroughs Local Plan, in which the occupation includes other uses, existing or proposed, beyond those referred in Sensitive Zones.

Neighbour Noise

Noise associated with the residential use and its related activities, produced by someone or by intermediate of others, by a thing in its custody or animal under its responsibility, which, by its duration, repetition or intensity, is susceptible of affecting public health or neighbourhood tranquillity.

Noise

Sound (variation of the sound pressure in a point) unwanted or unpleasant for a human being.

Noise Indicator

Physic-mathematical indicator of the a noise description that is related with a prejudicial effect on health or wellbeing.

Noise Indicator for Day (Lday or Ld), Evening (Levening or Le) and Night (Lnight or Ln)

Long-term average noise level, determined during a series of day, evening and night-time periods, respectively, representative of one year.

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Noise Indicator LAeq, T

Value of the A-weighted sound pressure level in decibels of continuous steady noise that, within a specified time interval, has the same mean-square noise pressure as a noise that varies with time, and is given by the following equation:

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Noise Map

External ambient noise descriptor, typically expressed by the Lden e Ln indicators, traced in a document showing the noise contours and its delimited areas, which correspond to a set value class in dB(A).

Noise Sources

Action, permanent or temporary activity, plant, structure or infra-structure that produces harmful or annoying noise for those o live, work and stay at locations where its effects are experienced.

Non Yet Classified Zone

Areas that the Local Authority is yet to classify in terms of acoustic exposure.

Observation Time Interval

Chosen measurement time interval, within the reference interval.

Permanent Noisy Activity

Activity developed permanently, even if seasonal, that produces harmful or annoying noise for those who live, work or stay in locations where its effects are experienced, particularly industrial, commercial or services noise.

Reference Time Interval (or Reference Period)

The time interval that a noise indicator references, comprising typical human activity, delimited in the following terms: daytime period – from 7 to 20 hours; evening period – from 20 to 23 hours; night-time period – from 23 to 7 hours.

Residual Noise

Ambient sound remaining at the assessment location when the specific sound source is suppressed to such a degree that it does not contribute to the ambient sound.

Reverberation Time, T

The time, in seconds, taken for the sound to decay by 60 dB after a sound source has been stopped.

Sensitive Receiver

Residential buildings, schools, hospitals or similar, or leisure areas with human occupation.

Sensitive Zone

Area defined in the Boroughs Local Plan dedicated to residential use, schools, hospitals or similar, or leisure areas, existing or proposed, that can include small commercial and services areas with the purpose to serve the local population, such as cafés and other restaurant uses, news stands and other similar local businesses, not trading in the night-time period.

Specific Noise

Part of the ambient noise that can be particularly identified by acoustic means and attributable to a specific noise source.

Standardised Airborne Sound Insulation, D2 m, nT

Sound pressure level difference between the average external noise level, measured at 2m from the building façade (L1,2 m), and the average noise level in the receiver room (L2), corrected for the influence of the reverberation in the receiver room.

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Standardized Airborne Sound Insulation, DnT

Standardised level difference between the average noise pressure level in the source room (L1), produced by one or more noise sources, and the average noise pressure level in the receiver room (L2), corrected for the influence of the reverberation in the receiver room.

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Standardised Impact Sound Insulation Level, L’nT

Average noise level (Li) measured within the receiver room, from a standardised impact source on a floor, corrected for the influence of the reverberation in the receiver room.

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Standardised Noise Rating Level, LAr, nT

A-weighted equivalent continuous noise level, for a specified time period, corrected for the noise tonal characteristics, K, and for the influence of the reverberant field within the receiver room.
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Temporary Noisy Activity

Activity that, although not an isolated act, does not have a permanent character and produces harmful or annoying noise for those who live, work or stay at locations where its effects are experienced, such as construction sites, sporting events, concerts, festivals and other entertainment events, fairs and markets.