Acoustical Consultants Research Articles

Application of a multi-criteria decision technique to assignation of acoustic classes

Acoustic performance evaluation of buildings prior to the acoustic classification, requires consideration of a number of factors with the corresponding quantitative criteria to be satisfied. It is of question how much the deviations can be compensated and whether all performance factors are equally important. This paper presents the results of a study on assigning priorities for each acoustic factor by using the analytic hierarchy process (AHP) - a multi-criteria decision technique - based on the expert evaluations. Eleven acoustic consultants rated seven acoustic factors, i.e. regulatory criteria of sound insulation, sound level and reverberation time, in pairwise comparisons. The data were aggregated after a consistency check and weights of each acoustic factor were calculated as well as weights of six acoustic performance classes ranging from A to F. The outcomes of this study resulted in a decision matrix, named as "acoustic scorecard" which can be used to obtain a single-number rating index for acoustic quality of buildings.

A collaborative approach to low-frequency noise mitigation

This case study examines efforts to study and mitigate low-frequency noise produced by boilers serving a large hospital. The work was completed by a collaborative group of citizens, hospital staff, acoustical consultants, and noise control solutions providers. While none of the noise controls are novel from an engineering perspective, the criteria, experimental methods, and consensus strategies used for this project could serve as a model for similar community challenges.

Applying the Association of Australasian Acoustical Consultants (AAAC) guideline for acoustic assessment of gymnasiums and exercise facilities to field measured heavy hard impact data.

In this paper we apply the newly published Association of Australasian Acoustical Consultants (AAAC) Guideline for Acoustic Assessment of Gymnasiums and Exercise Facilities to field measured heavy hard impact data. ISO and ASTM have working groups developing standards with regards to heavy, hard impact noise. There is an industry need for a single number rating or other evaluation system "to assess the noise and vibration impact resulting from the use and operation of both existing and proposed gymnasiums and exercise facilities consistently, accurately and fairly." Lmax sound pressure levels resulting from 22.7 kg weight drops from 150 mm height were collected in a concrete building on numerous gym flooring build ups in two different adjacencies. AAAC guidelines are applied, and single number ratings reported. The AAAC metric is compared to other existing guidelines and metrics. This brings to light the need for a comprehensive ASTM guideline for assessing structure borne noise associated with fitness areas in mixed use buildings.

Benchmarking the aircraft noise mapping package developed for a unified urban environmental modelling tool

Abstract In densely populated cities, residents living near aerodromes may experience heightened exposure to aircraft noise. With hybrid work arrangement, authorities have observed a rise in the number of complaints filed by residents affected by aircraft noise. In view of this problem, urban planners are now placing even more emphasis on exploring solutions that can manage aircraft noise in new and existing residential areas. To achieve this objective, urban planners usually rely on external acoustic consultants to generate noise maps using commercial software. However, urban planners may need to quickly evaluate potential noise issues in the neighbourhood so that noise management strategies can be brainstormed in advance. In this article, we present the development and benchmarking of a package designed to easily generate aircraft noise maps via simplified procedures and a reduced amount of input data, with acceptable accuracy in the results. These benefits distinguish our developed package from commercial software. Our developed package was eventually integrated into an in-house-developed unified urban environmental modelling tool that aims to help urban planners design more liveable and sustainable residential towns in an intuitive and quick manner.

Improving the persuasiveness of the noise consultant report—A critique and proposal

The author, a retired mechanical engineer and patent attorney, sat on an HOA Board that converted four tennis courts to 13 pickleball courts without installing the noise absorbing barrier recommended in three reports by two acoustical consultants. A nuisance lawsuit seeks an injunction to close the courts and money damages. Consultants study the pickleball noise and recommend mitigation options to the deciders. Deciders are laymen, such as city officials and HOA boards, unfamiliar with noise science and under pressure to meet the insatiable need for more pickleball courts. When mitigation is not implemented, or not successful, litigation ensues. Judge and jury become deciders. This paper starts from the premise that the consultant makes technically competent recommendations and is motivated to fully educate the lay deciders. We explore the communication gap between consultants and deciders. Proposals include embedding wav. noise files in the written report, reference to ANSI standards for highly impulsive noises, deference to the lack of research on health issues of long-term exposure to persistent repetitive impulsive noise. We introduce the missing metrics of “pickle pops per hour” and the “predictable worst case noise impact” occurring when intensively used courts are introduced into residential neighborhoods.

Development of an acoustic design support tool for HVAC ventilation units

HVAC equipment is one of the main sources of noise inside or outside a building. Furthermore, many people are exposed daily to HVAC noise, which can lead to health-related troubles. Therefore, an HVAC mechanical unit must be selected to provide an acceptable sound level transmitted to the occupied spaces of a building and not disturb the community. This paper presents a prediction tool named Sound Prediction Tool (SPT) developed by MJM Acoustical Consultants Inc. in 2021 that allows the engineer (i) to design an HVAC unit with specific mechanical components (filter, coil, etc.) according to his input parameters and (ii) to predict and optimize the sound levels produced by the selected design through its casing and openings (inlet and outlet air). This tool has been validated firstly with acoustical tests ‘’in situ’’ on several separate Air Handling Units (AHU) manufactured by our customer and secondly with Finite Elements Method (FEM) models using Comsol-Multiphysics. Several examples are presented to demonstrate the usefulness of the proposed tool.

Robotization of “in situ” acoustic measurements

Currently, “in situ” acoustic measurements require a high level of human involvement. Measurements are carried out by technicians or engineers, and most of the time, two people are required. MJM Acoustical Consultants Inc. has explored the possibility of using an autonomous and semi-autonomous robotic solution to assist in the measurement process. Developed in partnership with university Polytechnique Montreal, the research project consists of developing a software platform and hardware for a mobile robot capable of moving around, locating itself and performing measurements using a Type I sound level meter. The prototype generates its own local area network (LAN), making it possible to send commands through high-density partitions such as brick walls or concrete floors remotely from a laptop. Localization system such as a laser remote sensing system allows the robot to navigate around obstacles. Its low noise level when stationary makes it ideally suited to conduct common standard tests such as impact noise isolation, airborne sound attenuation between rooms and background noise level measurements. Through tests carried out on field sites, the solution developed constitutes an effective instrumentation to make acoustic measurements sessions more efficient with a reduced level of human operation.

Comparison of ASTC results with the calculation performed using the NRC soundPATHS calculator

The NRC has developed a calculator that predict the apparent Sound insulation, as described in the procedure described in Section 5.8.1.4. or 5.8.1.5. of the 2015 edition of the National Building Code of Canada. Since 1984, MJM Acoustical Consultants has performed a lot of ASTC tests in the field on the huge variety of building structures (wood, steel, concrete, steel/concrete, etc.) and on different types of partitions (wood or steel). Since the 2015 National Building Code of Canada has been enforced in January 2022 in the Quebec province, there will be in increased demand to perform calculation the soundPaths calculator. Therefore, the performance of the calculator compared to real life situations should be assessed. The purpose of this paper is to present several comparison of the ASTC rating measured in the field and the rating provided by the soundPaths calculator using the same partitions compositions and building structure . We will then discuss the difference between the results and proposed some improvements of the NRC SoundPaths calculator.

Application of soundscape methodologies in an acoustic consulting context

Understanding environmental sound from subjective perspectives is important for comprehending sound qualities beyond physical parameters. Soundscape approaches are promoted as valuable frameworks for understanding subjective experiences of environmental sound. However, the application of such approaches in acoustic consulting environments is limited and the demonstrated value is unclear. This study investigates the applicability of soundscape methodologies in a corporate consulting context. In this paper we summarise available soundscape methodologies and their known challenges, and test the application of select methods, including sound mapping and soundscape descriptors, in different acoustic consulting settings at Arup. Through practical application, we explore the contexts in which soundscape approaches may be used to document, assess and describe sound environments. We review barriers and limitations experienced through application, such as training, project constraints and the need for project-specific methodology adaptation, and discuss values that emerged, including an enriched understanding of sound qualities not otherwise captured through conventional acoustic approaches. We position this research as a step towards developing a soundscape toolkit for acoustic consultants and argue that the incorporation of a soundscape perspective in acoustic consulting is necessary to expand the ways in which we understand environmental sound and its effects on those within it.

Enhanced noise propagation due to atmospheric effects: Practical considerations—Part 1

How far should an acoustical consultant go to investigate enhanced noise propagation due to atmospheric effects? This paper was inspired by recent updates to Victorian noise policy, which includes more stringent requirements for consideration of atmospheric effects. The authors have identified an opportunity for development of a consolidated practical method for acoustical consultants to apply in Australian conditions. Predictive calculations implementing various standards can estimate atmospheric effects based on either broad assumptions, subjective observations, or detailed weather data. Acoustical consultants are often reliant on incomplete and potentially irrelevant weather data. This includes data from sources such as public weather stations far away or local weather stations close to ground level. This paper is the first part of a two-part study designed to inform a best practice method for acoustical consultants assessing atmospheric effects with respect to enhanced noise propagation. Part one, this paper, will review the current state of knowledge including different policy approaches and predictive standards. Part two would be a field study with concurrent detailed measurements of atmospheric conditions and noise levels to inform appropriate weather data collection methods and predictive standards for Australian conditions.

Challenges for flexible distance learning professional acoustics education

A fully flexible, distance learning program comprising a number of modules has been available for those entering the acoustics consulting industry for over a decade. The flexibility requested by the association for the Australasian Acoustical Consultants (AAACs), means each of the modules can be commenced at any time and there are no firm deadlines for completion. The program has been very successful with satisfied students and employers. Clearly there is a great benefit for such flexibility as the industry does not recruit new staff at times that fit the University semester system. Hence, other options such as a microcredential approach are not always suitable. Also the students are able to adjust their progress in accordance with the varying work pressures of consultancies. However, the open approach means that there are challenges for the management of the program. These include always being available for processing new applications, supporting and guiding current students, undertaking the marking as well as updating the content, assignments and tests. This paper will discuss the challenges and the changes that have had to be made and those that will need to be introduced to ensure the long term viability of the program.

The booming party walls being constructed in the skyscrapers of Toronto

With eight new 300 m or higher buildings and another ninety shorter skyscrapers either under construction or proposed for the booming Toronto real estate market, there is no shortage of work for acoustic consultants in Toronto at the moment. Most of the high-rise buildings allocated for residential use include concrete floors and ceilings, glass curtain walls, and lightweight, steel stud gypsum board interior walls. A party wall design that has become popular among architects is a double steel stud wall with one or more layers of gypsum board attached to the studs in the gap between the rows of studs in addition to the gypsum board attached to the exterior of the studs. Typically, the transmission loss values for the wall designs used to demonstrate compliance with the building code are those for single stud walls with equivalent stud gauges and numbers of exterior layers of gypsum board. Due to the lack of available data, the National Research Council of Canada measured the transmission loss of many of these wall designs and found that adding the gypsum board in the cavity between the rows of studs has a significant effect on the transmission loss below 200 Hz.

Single-value frequency-average measures of early decay time and clarity index to predict reverberance and clarity

The most accepted acoustical parameters for the assessment of concert hall acoustics are summarized in the Annex A of the ISO 3382-1 standard, along with recommendations that are important for the practical application of these parameters. These recommendations have their origin in the practical experience of acoustical consultants and a few scientific studies, and further research is needed to properly validate them. In particular, more information is needed on how to average the octave-band values of acoustical parameters to obtain single-value frequency-average measures (SVFA) that are better correlated with the associated perceptual aspects. In this study, SVFA measures of early decay time (EDT) and clarity index (C80) were obtained by means of a listening test in which 24 subjects rated a set of stimuli in terms of reverberance and clarity. The participants listened to auralizations of orchestral music convolved with measured spatial room impulse responses in an anechoic chamber using third-order Ambisonic reproduction. The results of the listening test indicate that the mid-frequency, 500 and 1000 Hz, octave-band average of EDT and the average of the 4000and the 8000 Hz octave bands of C80, have the highest sensitivity in the prediction of reverberance and musical clarity, respectively.

The development of the AAAC Guideline for Gymnasium & Exercise Facility Assessment and case study information

Association of Australasian Acoustical Consultants (AAAC) member representatives began discussing the need for AAAC guidance on impact noise from gyms in early 2016. This was in the absence of an agreed position or standard assessment criteria. It was identified that in addition to the overall target criteria the Guideline also needed to provide a standardised method to assess and test impacts and to determine compliance as well as guidance on suitable locations for the siting of gyms. This presentation provides an overview of the development of the AAAC Guideline for Gymnasium & Exercise Facility Assessment. The presentation also includes case study information to illustrate the application of the Guideline.

Use of Virtual Reality and auralization as a training tool for acoustic practitioners

Room acoustic qualities for performance spaces are described, including in ISO 3382-1:2009, in objective metrics such as reverberance, clarity (C80), early lateral energy fraction (JLF) or late lateral sound level (LJ). For acoustic practitioners, an understanding of these parameters and their subjective perception in venues is necessary to describe existing acoustic conditions and carry out acoustic designs of venues. Gaining practical experience of venues to understand the changes in acoustic qualities can be difficult for various reasons. Virtual Reality (VR) technology, combined with auralization from 3-D room impulse responses, generated by computer acoustic modeling of virtual spaces, makes it possible to generate virtual listening experiences to demonstrate room acoustic qualities. This presentation describes the development of a VR training video demonstrating various room acoustic qualities in a virtual concert hall. The video was intended for training of acoustic consultants to recognize and differentiate changes in room acoustic parameters for performance spaces. The VR video presented a number of scenarios where each showed a primary change in one of the qualities, through targeted manipulation of the virtual space. Following deployment of the training video, feedback was taken from users to assess the usefulness of the format for training purposes.

Rail noise across three states in Australia—Operational noise assessment on Inland Rail

Inland Rail Project is a proposed 1700 km freight rail line connecting Melbourne and Brisbane via three States in Australia–Victoria, New South Wales, and Queensland. Operational rail noise assessment is undertaken differently across these States in Australia. The assessment generally considers the existing and future noise exposure across day and night, along with single pass-by maximum levels. However, the assessment durations and statistical means of assessing single events differ across the States. The key acoustic criteria relevant to operational noise assessments and how they differ across the project footprint are discussed in this paper. Specifically, the effect of application of various criteria in the project context are discussed, along with statistical analysis of train pass-by noise data sets. A Monte-Carlo based methodology is proposed for estimating Single Event Maximum, a criterion for assessing single rail-noise events in Queensland. The methodology is discussed in the context of field data and greenfield scenarios where the method may be beneficial for acoustic consultants. The effects of inclusion of noise sources such as train horns and crossing bells are also briefly discussed. Finally, a proposed methodology for a consistent assessment of rail noise on such nationally spread projects is discussed.

Generative design of terraced concert hall – a case study of Taipei music and library centre

ABSTRACT The terraced concert hall offers a wide range of design options. Yet the knowledge barrier within a design team makes it difficult to effectively deliver a design that satisfies both the needs of creativity and acoustics. The study aims to explore the integration of generative parametric design collaboration workflow into the design of terraced concert halls and apply the cumulative results of the pilot study to the Taipei Music and Library Centre design competition. We propose an enhanced collaborating model between architects and acoustic consultants, integrating geometric design with acoustic verification in concert hall design. This cooperating model embraces and integrates three key steps: defining basic parameters and reference geometries, efficiently generating and composing geometric elements, and conducting geometric and acoustic statistical assessments. This design strategy enables integration of diverse viewpoints, covering both the acoustics within the hall and the space integration with the surroundings. The outcome is a terraced concert hall with an acoustic performance comparable to traditional shoebox-shaped halls.

Rezoning - beware of community noise problems

A common mission for an acoustical consultant is to anticipate and minimize noise problems for a community area in transition. Changes and resulting noise problems may be triggered by an industrial area that is rezoned by a city to encourage residential and mixed-use development or an agricultural area that is rezoned by a town to host light or heavy industry. Either way, potential noise-sensitive receptors, which are usually private residents, may be adversely affected and lodge noise complaints. A specific noise issue is many times compounded by non-acoustic factors such as traffic, smoke, smell, or visual impacts from the industrial development. This paper discusses historical calls for proper planning to address the goals of interested parties, including industry, government, and community groups, while minimizing the risk of community noise problems. In addition, this paper describes several examples where rezoning presented challenges and essentially forced industry and community developments to adopt noise control measures.

Which number is correct? Making sense of acoustical test results

Acoustical consultants and designers rely on sound data published by manufacturers to make informed design decisions. Even when manufacturers make efforts to communicate these data clearly, acoustical test values can be misinterpreted or misapplied. Nuanced sample mounting methods, specific test system configurations, and variability inherent in laboratory test methods are all factors that can affect test results and how or what data are published in manufacturer literature. Since at least the early 1950s, United States Gypsum (USG) has tested and published sound data for its products and systems. A brief history of USG’s acoustical testing and sound-related publications will be presented, along with examples of variability of results, influencing factors, and how this information is communicated to different audiences.

Auralization as a value management tool

Acoustical consultants tend to rely on written reports, verbal explanations, and drawing markups to convey the scope and meaning of our recommendations. However, since hearing is an inherently perceptive phenomenon, these modes of communication are indirect: they require users and clients to imagine the implications of important design decisions rather than experience them directly. Auralizations can help us fill in those gaps by allowing users to “get a sense” of an acoustical environment before it is built, literally hear how design decisions influence the acoustical outcome, and feel more confident moving forward with the best approach for their project. Most often, these experiences convince decision-makers to devote more resources to the acoustic design than they may have done otherwise, occasionally even going above and beyond the “best practice” recommendation. However, sometimes the simulated outcome of the light touch approach is deemed acceptable to the client, and in these instances, the auralization enables them to avoid the expense of overdesigning. This presentation will explore the spectrum from “client invests more than we expected” to “client reduces costs based on auralization” with a number of case studies related to client decisions that follow the auralization experience.