Acoustic Engineering Solutions (AES) provides consultancy services of aircraft noise impact assessment including aircraft noise modelling and measurements. AES uses the computer-based Integrated Noise Model (INM) to predict Australian Noise Exposure Forecast (ANEF) and generate noise contour mappings.
The INM was a computer model that evaluated aircraft noise impacts in the vicinity of airports. It was developed based on the algorithm and framework from the US SAE AIR 1845 standard, which used noise-power-distance (NPD) data to estimate noise accounting for specific operation mode, thrust setting, and source-receiver geometry, acoustic directivity, and other environmental factors. The INM could output either noise contours for an area or noise level at pre-selected locations. The noise output could be exposure-based, maximum-level-based, or time-based, including:
- Australian Noise Exposure Forecast (ANEF) charts;
- Noise Above Contours mappings of N60, N65 and N70; and
- Individual aircraft noise LAmax contour mapping.
Australian Noise Exposure Forecast (ANEF)
The Australian Noise Exposure Forecast (ANEF) is a scientific measure that takes into account meteorological conditions at the airport, forecast aircraft movement volume and frequency, allocation of these movements to flight paths and distribution over the day and night time periods, and the noise signature (intensity, duration and tonal content) and performance characteristics of the specific aircraft types.
The ANEF is used in conjunction with Australian Standard 2021-2000 ‘Acoustics – Aircraft noise intrusion – Building siting and construction’ (AS 2021) to provide the framework for land use planning and building treatments within the vicinity of an airport. AS 2021 places restrictions on the types of new developments which can be built within the various ANEF contours.
The ANEF chart illustrates noise contours plotted at 20, 25, 30, 35 and 40 ANEF units. The contour plot is the calculated total noise energy at that given point on the ground on an annual average day. The higher the ANEF value, the greater the expected exposure to aircraft noise in that area. Properties located within the ANEF 20 contour and above may have zoning and development restrictions placed on the land, noise insulation included as a condition of planning approval, and/or notification of the likely presence of aircraft noise on the land title.
Noise Above Contours
Compared to the ANEF, which is primarily a land-use planning tool, Noise Above Contour charts provide a more readily understood measure of noise exposure for the general public. These charts present the expected frequency of aircraft noise events on an average day that are above 60, 65 or 70 decibels (dB(A)).
The N60 Contours display the calculated daily aircraft noise events above 60 decibels. A 60 decibel outside noise corresponds to a 50 decibel noise event indoors, which is the sleep disturbance level specified in Australian Standard AS2021-2000. Similarly, the N70 Contours display the calculated average daily aircraft noise events above 70 decibels. A 70 decibel outside noise corresponds to a 60 decibel noise event indoors, which is the noise level specified in Australian Standard AS2021 as the indoor design sound level for normal domestic areas in dwellings that may interfere with activities such as normal conversation and watching television.
The Noise Above charts show the average daily noise events, calculated by dividing the total annual events by 365. For comparison purposes, N60 Contours have also been prepared for a ‘Busy Day’. The N60 Busy Day diagram shows the projected amount of noise events for a day where an Airport will be operating at its peak daily movement level (i.e. in extremely favorable weather conditions for flying training).
Individual aircraft noise LAmax
LAMax is an acoustic measure commonly used around the world to describe the highest instantaneous sound pressure level likely experienced during a single aircraft flight. LAmax provides some indication of interference with speech, listening to the television, sleeping or other common activities.
For small private airstrips, ANEF and/or Noise Above Contours may not be possible to be calculated due to the small number of aircraft movements. LAMax is the measure used for assessing aircraft noise impact.
DA Approval
Acoustic Engineering Solutions (AES) recently undertook aircraft noise assessments of several private airstrips for their DA approvals using INM. AES has many years experience in aircraft noise modelling and impact assessments, and happy to assist you with your DA approval of a private airstrip.
If requiring aircraft noise modelling and assessments, please do not hesitate to contact AES:
- 0408 944 982; or
- enquiries@acousticengsolutions.com.au