The correction for ground effect around airports is modeled based on the results of numerical analysis in order to make it possible to estimate the propagation of noise caused by ground operations in airports such as engine run-ups and APU to the vicinity of airports. The excess attenuation due to ground effects on sound caused by engine run-ups and APU is calculated using a PE method for typical jet aircraft and propeller aircraft, respectively. On the assumption that the ground around an airport consists of asphalt-paved surface and grass-covered surface in a certain ratio, the excess attenuation for the mixed impedance ground is calculated with the Fresnel-zone method using the results of PE calculation. The composition ratio of ground surface is assumed based on the composition ratio of asphalt-paved surface and grass-covered surface along the propagation path from the engine run-up spot to the airport site boundary of six major airports in Japan. In this paper, we introduce the excess attenuation calculated with the PE method and the correction model for ground effects on noise of engine run-ups and APU is discussed to implement it in the airport noise prediction model used in Japan.
This paper describes the results of a study to improve the calculation method for predicting aircraft noise around Japanese airports using our prediction model. The model limited the calculation frequency for the insertion loss caused by noise barriers and buildings to a single 250 Hz, which does not reflect the actual frequency spectrum of aircraft. Therefore, to simulate more realistic conditions, we calculated a synthetic attenuation chart from the frequency spectra of several representative aircraft models and included the chart in our model. We then compared the calculated values with the measured values to verify the validity and discussed the influence of this change on the airport noise contours. In addition, for noise propagation of engines and auxiliary power units on the ground, an improved calculation formula for ground surface attenuation, taking into account the ground condition, has already been reported. In this paper, we report on the implementation of this calculation formula in our model and discussion of the calculation results.
In Japan, Lden is currently used as an evaluation index for aircraft noise. It is based on the A-weighted sound pressure. It evaluates differences in noise loudness, but it does not necessarily take into account differences due to changes in sound quality. Over the past several decades, single event of aircraft noise has been significantly reduced. As a result, we have experienced a change from the "noisy" sound quality of the old generation jets to the "soft" sound quality of the recent aircrafts. Has the sound quality really improved, and has its improvement been evaluated? On the other hand, since the 2000's, we have sometimes experienced hearing the extraordinary tonal sounds from landing aircraft. It has the characteristics of pure tonal tone with 250-500 Hz and has a short duration and a prominent level fluctuation. Doessuch a sudden tonality change, which is also negatively perceived, not affect the evaluation? This paper describes the results of trial calculation in order to examine the possibility of evaluating aircraft noise considering its sound quality, based on several indices such as EPNL, loudness, sharpness, and Tonal Audibility (TA), in addition to the A-weighted noise (LAmax, LEA), and its comparative verification including differences in aircraft generations.
The Japanese segment model focuses on understanding noise impacts in the surrounding areas relatively close to the airport. The basic data to be prepared for predicting are usually the results of measurements and analysis in the area near the airport. In areas farther away from airports, the altitude of aircraft is higher, there is an issue that prediction results based on the basic data collected near airports accurately reflect the reality. Often, areas far from airports get complaints even if noise exposure was not high. There is a desire for a model that can predict with relatively high accuracy and ease even in locations far from airports like this. Based on this background, we have developed a simple prediction model based on actual observation results of noise and flight paths, which can be used as basic data for aircraft noise prediction. In this approach, a database is created using noise measurements obtained from unattended noise monitoring and short-term survey results and aircraft position information from the ADSB. In noise propagation calculations, predictions are made considering factors such as lateral attenuation of ground surfaces, air absorption, and variability in flight paths by a simple method.
Long-term level fluctuation of airport noise was investigated, in relation to meteorological conditions, using observation data of unattended noise monitoring system of airport noise including fly-over noise, engine run-up noise and other airport ground noise due to APU operation, towing and so on. This paper not only describes the procedure that classifies the observed noise events being based on information about sound arrival direction and airport operation, but also shows results of level conditions. (A) For the covering abstract see ITRD E113232.
In Japan, noise index for evaluating airport noise was changed from WECPNL to Lden, which will be enforced from April, 2013. It was also decided to take aircraft ground noise within the airport when necessary. As a part of these ground noise components, it is necessary to take account of noise contributions due to APU operation on the apron before take-off, after landing, or maintenance during the midnight. This presentation explains a brief summary of an investigation of sound source characteristics of APU noise and compares noise calculations using the result with measurements observed by unattended noise monitoring devices.
In Japan, systematic countermeasures against aircraft noise have already been implemented since the 1970s. It is also in accordance with the later ICAO Balanced Approach. The measures could be divided into three main categories, which are reducing of noise source, Improvement of airport structure and facility, and countermeasures for remedial compensation. The priority strategies were placed on introduction of low-noise aircraft, restrictions on night flights, construction of offshore airports, and remedial compensation such as soundproofing for houses etc. As a result, by the 1990s, compensation measures for severe noise were completed, and nighttime flight restrictions prevented health effects resulting from sleep disturbance. However, since the beginning of the 2000s, residents' acceptance of aircraft noise has changed, and issues have appeared regarding not so loud noise at locations far from airports. In addition, some airports are expanding late-night operations to meet the recent growth in aviation demand. This paper describes the review of strategies of mitigation countermeasures for aircraft noise in Japan and current issues such as the new phase for making coexisting with surrounding residence area in currently, and the need for strategies.
At the side of flight path, especially on the side of runway, noise level observed greatly changes dependent on the effects of excess ground attenuation and meteorological conditions (in particular, vector wind and temperature gradient). Thus, taking account of appropriate adjustment for lateral attenuation in airport noise modeling leads to an increase in the reliability of predictions. This paper makes a review of equations for lateral attenuation such as SAE/AIR 1751, SAE/AIR 5662, and our equation 1751M, which is a modified equation we proposed based on AIR/1751 and is applicable under various meteorological conditions. It is also described with further issues related to the examining of lateral attenuation for aircraft flyover noise. In Japan, it is obligatory to take into account noise contributions of aircraft ground operations such as APU operation, taxiing, and engine run-up in airport noise modeling. However, we have not yet fully examined whether we can evaluate lateral attenuation of such ground noise similarly to flyover noise. It is not yet solved how to calculate excess ground attenuation under the effects of sound shielding by barriers or embankment. This paper also discusses how to evaluate lateral attenuation for noise due to aircraft ground operations.
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)