Dóris Queirós, Rui Calejo Rodrigues, Nelson Pereira
Historic buildings that regularly characterize the centre of our cities present us the challenge of being updated without losing their uniqueness. Acousticians frequently find themselves at the centre of this challenge, facing traditional solutions that must fulfil contemporary acoustical requirements. In order to apply technical improvements to enhance the performance of traditional solutions, the first step is to understand how these solutions work and perform in real-life conditions. Traditional solutions were conveniently tested by site measurements for validation. Airborne sound insulation (DnT,w) and impact sound insulation ([Formula: see text]) tests were performed on 13 similar wooden floors. The same wooden floor was constructed at the Faculty of Engineering in University of Porto’s acoustic chamber in order to study its acoustical behaviour without the influence of flanking transmissions. Wooden floor improvement solutions were tested through the addition of airborne and impact sound insulation favouring materials. Airborne sound insulation (Rw) and impact sound insulation (Lnw) tests were performed on six solutions for the improvement of the traditional wooden floors. Traditionally, in Portuguese historical buildings, the lack of knowledge of the traditional solutions’ technical characteristics is sometimes the reason for demolishing these solutions. Adapting traditional solutions to current standards of comfort can become arduous since the information on the performance of these solutions is unknown. The potential demonstrated by these enhanced traditional solutions predicted a shift in current paradigms and will allow acousticians to support the challenge of historic building retrofit.
Abstract This paper presents an overview of basic concepts, features and difficulties of the boundary element method (BEM) and examples of its application to exterior and interior problems. The basic concepts of the BEM are explained firstly, and different methods for treating the non-uniqueness problem are described. The application of the BEM to half-space problems is feasible by considering a Green's Function that satisfies the boundary condition on the infinite plane. As a special interior problem, the sound field in an ultrasonic homogenizer is computed. A combination of the BEM and the finite element method (FEM) for treating the problem of acoustic-structure interaction is also described. Finally, variants of the BEM are presented, which can be applied to problems arising in flow acoustics.
The aim of this research is to demonstrate the importance of initial strategies in acoustical design of underground metro stations. The paper searches for practical design solutions by evaluating different materials for providing optimum acoustical conditions in such spaces. Acoustical designs of three metro stations on a new expansion line in Ankara including Sogutozu, Bilkent and ODTU metro stations are presented through computer simulation. Predictions of room acoustical parameters are presented for both platform and ticket office floors in terms of parameters like reverberation time (RT), speech transmission index (STI) and A-weighted sound level (SPL) distribution within spaces. Simulated reverberation times are evaluated in view of legislative requirements. The study confirms the importance of using sound absorbing materials on the ceiling and sidewalls together. The nonwoven material, used behind perforated metal suspended ceilings, has proved effective in reverberation control.
The University of Hartford has provided the author with a fulfilling métier, shepherding two undergraduate engineering programs in the area of acoustics: (1) the Bachelor of Science in Mechanical Engineering (BSME) with Acoustics Concentration and (2) the Bachelor of Science in Engineering with a major in Acoustical Engineering & Music. The first is part of our BSME degree program that has required courses in Vibration as well as Engineering Acoustics since the 1960's. The Acoustical Engineering & Music degree is a unique program instituted in 1976, where applicants must meet engineering’s math and science entrance requirements as well as pass the audition requirements of our music conservatory (The Hartt School). Both ABET-accredited programs encompass the same engineering vibrations and acoustics courses, as well as the same acoustics projects sequence, beginning in the sophomore year. Alumni of both undergraduate programs have successfully obtained positions in consulting (architectural and environmental), audio product and A/V design, musical instrument design, hearing- and psychoacoustic-related design, noise/vibration control of machines, as well as graduate degrees. The use of real world industry-sponsored acoustic projects for engineering design courses throughout the curriculum will be described, as well as the programs’ Service Learning components and High Impact Practices.
Recently Committee E-33 of the American Society for Testing and Materials (ASTM) proposed a new standard, Guidelines for the Preparation of the Accreditation Section of Acoustical Test Standards. The Guidelines recommend that a section on laboratory accreditation be included in every acoustical test standard to inform accrediting authorities what requirements should be satisfied by the facilities, instruments, procedures, and quality assurance program of an accredited laboratory. The accuracy required for test instrument should be specified, and accredited laboratorie should be required to demonstrate that test instruments satisfy the specifications. Both the accreditor and the accredited laboratory—in fact anyone who uses acoustical instruments—should understand what constitutes traceable calibration of test instruments. A panel will discuss the problems and requirements of traceable calibration. The panel will include representatives of: • the National Bureau of Standards, • the National Research Council of Canada, • instrument manufacturers, • laboratory managers, • acoustical consultants. The audience will be invited to participate in the discussion.