Noise Prediction Software Research Articles

Road noise mapping of Medellíńs downtown: Experiences, analysis of different calculation’s methods, and noise prediction software.

In this paper we will present the development of road noise map in the downtown of Medellin City through the implementation of predictive software. For the construction of noise mapping, the results obtained using the calculation’s French method (NMPB) and German method (RLS 90) were compared. The prediction process was carried out using two different softwares (SOUNDPLAN and CADNAA) for the purpose of analyzing the differences in the programs and the resulting levels. Finally, noise measurements were made in order to validate the prediction.

The development of a practical framework for strategic noise mapping

There currently exist a number of commercial tools which may be used to develop strategic noise maps in an effort to satisfy the requirements of EU Directive 2002/49/EC. However, these tools may not be readily available to local authorities with limited resources. This paper investigates the possibility of developing a simplified alternative to using detailed commercial software for the creation of strategic noise maps. In-house noise prediction software was used to calculate a noise map of Dublin city centre and results were compared to those of commercial standard software. The in-house software tool was then used to assess the impact of various source-dependent action plans in a time-efficient and practical manner. Measurements were also carried out at various locations throughout the test area, which were then used to investigate the accuracy of predictions. Finally, a hybrid approach to developing a strategic noise map by integrating measurements taken on-site with predictions was developed. This approach was applied to the test area and yielded a refined noise map that presented noise levels which were more reflective of the measured levels recorded on-site. This demonstrated that the method could be used to determine noise levels that would be representative of the acoustic environment experienced on-site.

Aircrafts' Taxi Noise Emission

An investigation has been conducted, with the objective of creating a database of inputs that can be used with noise prediction software, to evaluate noise of aircraft taxing movements and community noise exposure levels. The acoustic consultant can use these data with any of the software packages, to simulate taxing, by moving point source. ISO 3744 Standard is used, to estimate sound power levels emitted by a noise source and helps in describing a procedure based on sound pressure level measurements in a free field over a reflecting surface. The main steps that are involved in the procedure, include a measurement surface grid needs to be defined, to envelope the noise source and linear averaged third octave band spectra needs to be measured for all microphone locations.

Using the soundscape approach to develop a public space in Berlin - measurement and calculation

In this contribution the Soundscape Project “Nauener Platz” in Berlin is subject to different measurement- and calculation methods to develop acoustical indicators and parameters into a database describing urban and other outdoor living areas with respect to physical conditions and their relevance for life. The “Nauener Platz” is carried out to rebuilt a difficult open space into a space which is dominated by social freedom. To obtain the physical quantities sound pressure levels in 1/3-octave bands were measured and artificial head recordings were taken to describe the current state. Combined with calculations using noise prediction software it was possible to verify the sound propagation data outside according to the measurements and allow predictions about planned arrangements. First estimations of these measurements and calculations will be presented. The Soundscape Project is a module of the Project “Nauener Platz - remodelling for young and old”. This project is in the framework of the research program “Experimental Housing and Urban Development (ExWoSt)” of the “Federal Ministry of Transport, Building, and Urban Affairs (BMVBS)” by the “Federal Office for Building and Regional Planning (BBR)”. It is related to the fields of research (ExWoSt) concerned with “Innovation of Urban Neighbourhoods for Families and the Elderly”. The project executing organization is the Regional Office Berlin-Mitte.

Aircraft Noise

Various noise measurement parameters/indices used to define aircraft and airport noise are explained. The noise zone limits used around airports in some countries are given. Noise prediction software can be used to generate noise contours around airports. New aircraft noise certification standards have been developed to encourage control of aircraft noise at source. Aircraft noise can also be reduced if noise abatement landing and take-off procedures are followed.

Quirks, problems, and work-arounds with ray-tracing software

More and more, acoustical consultants and those in industry are turning to commercially available community noise prediction software to assist in assessing and mitigating community and environmental noise impacts. End users come from varied backgrounds that range from the novice to the expert in noise prediction or using noise ray-tracing software. What could start out as an expectation of a faster and more effective method of analyses, often turns into disappointment and frustration, if not total exasperation. Furthermore, hours upon hours of wasted effort and budget overruns can occur while learning to effectively use the software package chosen. This typically stems from a lack of adequate tutorials or training, apparent errors in the software, poor documentation, undocumented restrictions, lack of ease in learning and using the software, etc. This paper identifies some of the problems often encountered while modeling industrial facilities, propagation path influences, and receivers. In addition, some problems found in basic acoustic modeling are also identified and reviewed. In certain instances, work-arounds have been found, which allow the modeling process to continue with reasonable accuracy.

Issues in predicting community noise for power plants

The normal method of predicting community noise levels involves first computing sound power levels from near-field sound-pressure levels and then assuming that the noise radiates from one or several point sources. This approach makes several major leaps of faith. Some of these leaps of faith or issues in predicting community noise levels for power plants are identified. The issues include validity of near-field sound-pressure levels, accuracy of sound power levels computed, radiation from large sources, transmission through building walls, and screening and reflection of noise by power plant equipment and buildings. The validity of representing large sources as one or a series of point sources is reviewed. The role of atmospheric effects and the dangers inherent in typical noise prediction software is briefly reviewed. Several examples and suggestions for making more accurate predictions are given. [See NOISE-CON Proceedings for full paper.]

On the prediction of propeller tone sound levels and gradients in an airplane cabin (benchmark utility)

An advanced version of the propeller airplane interior noise (PAIN) model [L. D. Pope, J. Acoust. Soc. Am. 88, 2755–2765 (1990)] can generate a prediction of the variation of the cabin cross-section average sound-pressure level of a transmitted propeller tone. The prediction can then be averaged along the length of the cabin to obtain the cabin volume average sound-pressure level, the latter being the only quantity that the original version of the PAIN model [L. D. Pope, E. G. Wilby, and J. F. Wilby, J. Sound Vib. 118, 449–467 (1987); L. D. Pope, C. M. Willis, and W. H. Mayes, ibid. 118, 469–493 (1987)] calculated. Of considerable interest is a comparison of the two volume average predictions because the advanced and original models are based on fundamentally different types of analyses. The original model predicts the response of each individual acoustic mode caused by each structural mode, leading to the average sound-pressure level within the cabin volume. The advanced version predicts the response of the entire complement of acoustic modes having a common cross mode index for each exciting structural mode. The average sound level in cabin cross section is obtained, as well as the cabin volume average. Close agreement in the two predictions of the average cabin level yields a higher level of confidence in both prediction results, compared to the independent predictions, particularly in circumstances where comparisons with flight measurements are minimal or nonexistent. Recently, during parametric studies, modifications were made to the advanced model to obtain better agreement between the two average predictions. This paper presents the revisions (upgrades) that were found to be necessary for consistency in the cabin trim absorption models. A demonstration is given of the present prediction capability through example benchmark calculations for two representative airplanes. Finally, the general usefulness of benchmark calculations and necessity of validation efforts in the development of interior noise prediction software are discussed.