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The sound field model of an irregular enclosure with two elastic walls and an inclined wall is established by the modal theory. The modal parameters of the irregular enclosure are obtained by the envelope rectangular technique. The influence of the inclination wall angle on the sound field in the irregular enclosure is discussed. When the inclination angle is increased from 0° to 45°, the resonance frequencies of the acoustic enclosure are basically reduced in the frequency range of 0∼250 Hz. When the inclination angle is increased from 0° to 45° every 15° interval, the amplitude of a certain acoustic mode itself decreases, while the amplitudes of the acoustic modes coupled to it basically increase. The acoustic potential energy peaks in the enclosure basically shift to the low frequency with the increase of the inclination angle. Furthermore, the change trend of the acoustic potential energy is regular in the low-order modes, but relatively chaotic in the high-order modes. In addition, in order to verify that the accurate description of the primary sound field is the basis of effective noise control, the two-elastic plate model is deliberately treated as one-elastic plate model, and its influence on the performance of active noise control is discussed. Also, if the multi-elastic plate model is regarded as a simplified automobile cab, the research results can be used for the preliminary acoustic design of the cab; that is, the research results can be used for the acoustic design of similar models.

This article discusses the integration of acoustic design approaches into architectural design education settings. Solving architectural acoustic problems has been for centuries one of the primary aims of theories and experiments in acoustics. Recent contributions offered by the soundscape approach have highlighted broader desirable aims which acoustic designers should pursue, fostering ecological reasoning on the acoustic environment and its perception as a whole. Drawing from the available literature, some examples are brought to show the integration of architectural acoustics and soundscape approaches into the realm of architectural design education, highlighting the significance of specific design situations and aural training techniques in learning contexts.

Hearing impairment is a part of the natural ageing process for many people, similar to the occurrence of wrinkles on the face. In order to improve the quality of life for old age seniors, it is necessary to provide a built environment that is appropriate for hearing impairment. The listening ability of the elderly is significantly diminished, particularly in noisy and reverberant environments due to hearing loss. A basic design guideline for houses built for hearing impaired seniors is that excessive noisy and reverberant environments should be avoided. The purpose of this paper is to develop housing acoustic design guidelines that consider hearing loss due to old age relative to natural factors of everyday life, through a detailed literature review. The guidelines take into consideration floor impact sound, heavyweight floor impact sound, unit-to-unit sound insulation, indoor background noise sources, reverberation time, ceiling height, light–fan switch, bell–chime system and illumination level.

The present study investigates an optimum combination of absorptive and diffusing treatments for achieving preferred acoustics in classrooms. The measurements were carried out in a 1/10 scale model classroom, adding different amounts of absorptive and diffusing materials to one or more of five surfaces of the room. Adding diffusers on 25% of the ceiling area with the other 75% absorptive was more beneficial for achieving higher G50 and G values than adding absorptive materials on the entire ceiling. Adding absorptive materials on the entire ceiling area and diffusers on the front or side wall was beneficial for achieving shorter T30, EDT values and higher C50 values. Adding diffusers on the front or side wall slightly increased G50 and G values by more than 1 JND. Adding diffusers on the ceiling and lower front wall or side wall and adding diffusers on the ceiling a absorptive materials on the lower front wall were selected for consideration as the more successful treatments for classroom acoustic design.

Non-rational uniform B-splines (NURBs) are liberating acoustic design. Geometrical acoustics is no longer limited to flat surfaces. For decades, curved surfaces in computer models had to be broken down into a series of contiguous flat surfaces; a procedure prone to inaccuracy. With NURBs this is no longer the case. A new software tool has been developed by the authors, called NRAT, intended to facilitate acoustic design in NURB based geometries. Two parameters have been developed to quantify the efficiency of reflectors as they are being designed. They are called Reflector Efficiency (RFE) and Receiver Coverage (RCC). The two are quoted together, much like a blood pressure reading might be. The two parameters are required for reasons that became apparent to the authors as the NRAT tool was being developed. A small reflector, perhaps one that might be part of an array, may have a very high percentage of its surface area effectively casting reflections to the audience (perhaps 85%) but those reflections may only cover a small proportion of the audience area (say, 12%). Conversely, a large reflector, for example the side wall of a shoe box shaped concert hall, may only have a small area casting reflections to the audience – in our experience, in the range of 6%. But this small zone efficiently casts reflections across the expanse of the audience, sometimes as much as 90% or more. The quantification of the two RFE/RCC scenarios presented above would be, respectively, “85 over 12” and “6 over 90”. Two case studies are presented.

In this paper we describe one case of acoustic of refurbishment design. It is the refurbishment of Concert Hall of “Tonhalle St. Gallen. The centennial St. Gallen Concert Hall in Switzerland was a hall with many issues relating to the stage. High levels of sound, focusing, flutter echoes, and so on; the problem was never solved. The Director of the Orchestra and his musicians were generally very unhappy with this hall. In the last paper we analyse the St. Gallen Concert hall before refurbishment. In the Tonhalle St. Gallen the diffuser occupies only of stage area, but RT, EDT and G all are increased in audience zone, but in stage the G is decreased 3dB. The response by musicians, audience, and critics has been overwhelmingly favorable. Further research is needed to elucidate the mechanisms by which the labyrinth achieves these improvements, but the results in these venues suggest that this type of structure has an important role to play in acoustic design, particularly in smaller venues.

The scattering coefficient has been regarded as one of the important factors to be considered in the acoustic design of a room. ISO 17497-1 provides a method for measuring the random-incidence scattering coefficients in a reverberation chamber. However, the uncertainties of this method due to the lack of details with respect to the measurement conditions have been reported. It is necessary to provide more specific guidelines for this method. The present study suggests an improved measurement method by investigating the edge effects. The scattering coefficients of a simple 1-dimensional diffuser were measured in a 1/5 scale model of the reverberation chamber based on ISO 17497-1. The effects of an edge strip on the scattering coefficients were measured and analysed. Further, several issues with respect to the sample diameter, the air gap below the turntable and the absorption of the test sample were discussed.

Today most acoustic consultants are using room acoustic computer models as a basis for their acoustic design. However, room acoustic scale modelling is still being used for the design in some major projects, although the costs and the time needed are significantly larger than those related to computer modelling. Both techniques were used by the author in a project for a new opera theatre; first the acoustical design was based on computer simulations using the Odeon software, and next a 1:20 scale model was built and tested. In the paper the results obtained with the two different modelling techniques are compared, and in general a satisfactory agreement has been found. The advantages and drawbacks related to each of the modelling techniques are discussed.

Acoustic performance is an inevitable part of architectural design. Our sonic experience is modified by the geometry and material choices of the designer. Acoustic performance must be understood both on the level of material performance and also at the level of the entire composition. With new parametric and scripting tools performance driven design is possible. Parametric design and scripting tools can be used to explore not only singular objectives, but gradient conditions. Acoustic performance is often thought of in terms of singular performance criteria. This research suggested acoustic design can be understood in terms of gradients and multiple performance parameters. Simulation and modeling techniques for computational acoustic prediction now allow architects to more fully engage with the phenomenon of sound and digital models can be studied to produce data, visualizations, animations, and auralizations of acoustic performance. SmartGeometry has promoted design methods and educational potentials of a performance-driven approach to architectural design through parametric modeling and scripting. The SmartGeometry workshops have provided links between engineering and architecture, analysis and design; they have provided parametric and scripting tools that can provide both a common platform, links between platforms, but importantly an intellectual platform where these ideas can mix. These workshops and conferences have inspired two projects that both used acoustic performance as a design driver. The Smithsonian Institution Courtyard Enclosure and the Manufacturing Parametric Acoustic Surfaces (MPAS) installation at SmartGeometry 2010 are presented as examples of projects that used sound simulation parametric modeling to create acoustically performance driven architecture.

This article deals with the design and weight optimization of a multi-functional vehicle body panel in an automotive context. An existing vehicle design has provided functional design requirements regarding static, dynamic, and acoustic behavior of the components of a car roof. A novel, multifunctional panel is proposed which integrates the component requirements present in a traditional roof system within a single module. The acoustic properties of two configurations of the novel panel are examined using numerical methods including advanced poro-elastic modeling tools compatible with Nastran, and compared with numerical results of a finite element model of the existing construction.

The UK is undertaking a large-scale rebuilding of its school stock. The scale of the operation has meant that designers with little knowledge of school design are frequently involved. One negative consequence of this can be poor acoustic design and therefore a poor indoor environment. This paper is in part pedagogical, and presents a series of new key relationships in the acoustics of school spaces with an emphasis on dining rooms — an area with which architects have been found to have difficulties. Hopefully, this work will allow architects and building services engineers to appreciate better various salient points and to understand fully the flexibility they have to design novel spaces that can provide a high quality educational experience. Several novel equations are derived that acousticians, building services engineers, and architects may feel useful during the early stages of the design process. Three case studies are also given.

Our cultural climate is increasingly dependent upon visual space. Media and communication for the most part are exemplified through television and the Internet. Aural space has, for the moment, become an ambient presence. The aim of this article is to develop a phenomenological approach to interpreting our sonic environment by drawing upon a range of sound-scape theorists. I will, in some cases, provide a counter-argument to established theses, and in doing so endeavour to open up fresh debate for future sonic enterprises.

A neural network analysis was undertaken to relate the acoustic quality of concert halls to Beranek's six acoustical parameters: IACC, Gmid, EDT, BR, SDI, and TI. The results of the analysis are difficult to generalise but the present work indicates that there is still no reliable method of predicting the acoustic quality of halls. The limitations of the data and the methodology are explained and the results of the analysis are applied to the Concertgebouw, in Amsterdam, to see how changes in the acoustic parameters might change the acoustic quality of this hall. It is also shown that several different combinations of parameters can give reasonable predictions of acoustic quality. Finally, it is shown that there may be a better way of predicting the acoustic quality of halls which uses some of Beranek's acoustical parameters and the number of seats in the hall.

Paul Eade, General Manager of Acoustic Design Ltd., describes how railways offer him and his team of noise control and vibration engineers varied and interesting technical problems

Research over the last forty years has resulted in many new factors being considered in the acoustical design of concert halls. In this paper a brief account is given of this research and how halls designed since the nineteen fifties have been progressively influenced by this work. The Segerstrom Hall in California is an example of a hall where acoustical considerations have been given great importance at all stages of the design process and a team of consultants has ensured that recent research findings have been applied to good effect. The design approach is discussed and model experiments performed in the course of the design process are described. Finally the results of objective and subjective measurements carried out in the completed hall are described.

The case study takes Sharjah International Airport, located in one of the Emirates in the Middle East, and covers the broad field of mechanical, electrical engineering (building services) and acoustic design aspects. The paper includes a number of pre-design studies. It then sets out the design criteria adopted and the description of each of the engineering and acoustic elements. Reference is made to the testing and hand-over and the form of contract adopted.

Acoustic design is an important consideration in mechanical services installations of all types and, with this in view, maximum noise levels in buildings are commonly specified by reference to either noise criterion (NC) or noise rating (NR) curves. Although these rating methods have existed for some years, confusion still arises from time to time regarding their use and appropriate measurement procedures. This Note is intended to assist engineers who are not primarily acousticians, but who are nevertheless charged with taking accurate and representative measurements to monitor and certify performance standards. The origin and applicability of rating indices are summarised and practical guidance given on field measurements.