Architectural Acoustics Research Articles

Binaural speech intelligibility for combinations of noise, reverberation, and hearing-aid signal processing.

Binaural speech intelligibility in rooms is a complex process that is affected by many factors including room acoustics, hearing loss, and hearing aid (HA) signal processing. Intelligibility is evaluated in this paper for a simulated room combined with a simulated hearing aid. The test conditions comprise three spatial configurations of the speech and noise sources, simulated anechoic and concert hall acoustics, three amounts of multitalker babble interference, the hearing status of the listeners, and three degrees of simulated HA processing provided to compensate for the noise and/or hearing loss. The impact of these factors and their interactions is considered for normal-hearing (NH) and hearing-impaired (HI) listeners for sentence stimuli. Both listener groups showed a significant reduction in intelligibility as the signal-to-noise ratio (SNR) decreased, and showed a reduction in intelligibility in reverberation when compared to anechoic listening. There was no significant improvement in intelligibility for the NH group for the noise suppression algorithm used here, and no significant improvement in intelligibility for the HI group for more advanced HA processing algorithms as opposed to linear amplification in either of the two acoustic spaces or at any of the three SNRs.

A primer on low-carbon design in architectural acoustics using a case study of residential floorsa).

Designers are increasingly tasked to reduce the carbon footprint of buildings. While core disciplines (e.g., mechanical and structural) are determining sustainable design strategies, understanding the environmental impacts of architectural acoustics is nascent. Yet, acoustic design decisions provide opportunities to minimize building carbon emissions while ensuring suitable acoustic performance. In response, this paper first motivates the need for design synergies between architectural acoustics and sustainability practices. Second, this paper educates and equips acousticians to participate in sustainable design decisions by demonstrating a life cycle assessment framework to inform the selection of low-carbon floor-ceiling assemblies in residential buildings while satisfying sound isolation requirements.

Embedded Rough-Neck Helmholtz Resonator Low-Frequency Acoustic Attenuator

In various practical noise control scenarios, such as duct noise mitigation, industrial machinery, architectural acoustics, and underwater applications, it is essential to develop noise absorbers that deliver effective low-frequency attenuation while maintaining compact dimensions. To achieve low-frequency absorption within a limited spatial volume, this study proposes an embedded Helmholtz resonator featuring a roughened neck and establishes a numerical computational model that incorporates thermos viscous effects. A quantitative investigation is conducted on three types of embedded rough-neck geometries (rectangular-grooved, triangular-grooved, and undulated) to elucidate their acoustic performance, with particular attention to differences in acoustic transmission loss and acoustic impedance characteristics. In response to the practical demand for even lower-frequency attenuation, this work further focuses on optimizing the structural parameters of an embedded rectangular-grooved Helmholtz resonator (ERHR). A back-propagation (BP) neural network models and predicts how structural parameters impact the acoustic transmission coefficient, elucidating the effects of geometric variations. Moreover, by coupling the BP network with the Golden Jackal Optimization (GJO) algorithm, a BP-GJO optimization model is developed to refine the structural parameters. The findings reveal that the proposed method significantly improves resonator spatial utilization at a specific noise frequency while preserving acoustic transmission loss performance. This work thereby provides a promising strategy for designing low-frequency, compact Helmholtz resonators suitable for a wide range of noise control applications.

“Faith Not Works”: Chance Encounters and the Origins of Britain’s First Consultancy in Architectural Acoustics

Abstract Britain’s first independent architectural acoustic consultancy came into being at the close of World War I. Given the demonstrated disinterest in and lack of credence afforded to acoustics in architectural education and the complications encountered in incorporating acoustics into building design in Britain prior to the war, the emergence of a professional consultancy was neither predictable nor systematic. Yet this new direction in architecture did emerge, arising from a particular set of circumstances and a confluence of mindsets. Through an examination of the origins of that consultancy, this article weaves together the threads of chance, intellectual cohesion, and wartime circumstances that set the stage for a new form of applied design and scientific expertise. By drawing on personal letters, diaries, war documentation, government correspondence, and contemporaneous journals, it maps a trajectory of thought and interdisciplinary collaboration that took shape under the most unlikely of circumstances.

The Role of Sound in Shaping Architectural Spaces: A Multisensory Approach

The integration of sound within the built environment represents a pivotal yet often overlooked aspect of architectural design. This study explores the multifaceted dimensions of sound incorporation, emphasizing its potential to profoundly impact spatial experience and individual well-being. Through a comprehensive review of the literature, the study elucidates the diverse roles sound plays in shaping human perception, social interactions, and environmental quality. Sound, as a fundamental element of sensory experience, significantly influences our perception of space and place. Whether through the subtle ambiance of natural sounds or the deliberate orchestration of architectural acoustics, sound has the power to evoke emotions, establish atmosphere, and define spatial boundaries. Incorporating sound consciously into architectural processes presents opportunities to enhance the quality of life for inhabitants. By prioritizing acoustic comfort and fostering sonic diversity, designers can create environments that promote relaxation, productivity, and social cohesion. Furthermore, leveraging technology and design strategies enables the optimization of soundscapes to mitigate negative sounds and improve overall environmental sustainability.

The development of a new technical regulation on acoustics in buildings in Croatia

Even though Croatia gained its independence 32 years ago, up till now its legislation has not regulated the requirements that concern the acoustics in buildings. Instead, the regulations inherited from the former state of Yugoslavia were left in effect and have remained in use even after they were officially withdrawn, as no new regulations were adopted to replace them. To address this issue, a committee has been formed of experts affiliated with relevant governmental and professional organizations, and representing their respective fields of expertise, with the task of developing the new Technical Regulation on Acoustics in Buildings in Croatia. This document is to set detailed technical requirements on sound insulation as the means of protection from outdoor and indoor noise, the maximum permissible levels of indoor noise caused by service equipment, and the room acoustics design criteria for achieving optimal acoustics and/or as a noise reduction measure, to be partly or fully applied to a wide range of public and privately-owned buildings, with exceptions such as dedicated performance venues like concert halls or theatres. This paper presents the motivation for creating this document, its scope, and key aspects, as well as a brief overview of similar endeavors in the past.

Variability of low frequency laboratory measurements of acoustic isolation of floor/ceiling assemblies

It has long been recognized that building acoustics measurements performed in laboratories exhibit a high degree of variability between and within labs. Traditional metrics limited the use of data to above the 100Hz or 125Hz one-third octave bands. In recent years, focus has widened the range of frequencies of interest to the 50Hz one-third octave band or lower. Analyzing measurements of low frequencies in buildings is complicated by the physical reality of wavelengths that are similar in scale to common room dimensions resulting in modal behavior and the mathematical simplification of the wave equation in building acoustic calculations that assumes a diffuse field which discounts both phase and angle of incidence. Evaluation of common building isolation measurements of the same test floor/ceiling structure sample in the same lab and between labs across the frequency spectrum allows the comparison of the repeatability and reproducibility at low frequency ranges to those at high frequency ranges. Measurements and their associated metrics of various sources, including pink noise produced by loudspeakers, the standard tapping machine, and the impact ball are included in the analysis.

A high-resolution acoustic goniometer for characterizing sound diffuser reflections

Noise control engineering and architectural acoustics practice have widely applied diffusing elements and devices to create surface scattering and diffuse reflections. An acoustical goniometer in the form of a circular microphone array has been used to characterize scattered responses for various types of diffusing elements/devices. This research is also intended for experimental validation of diffraction simulations of diffusing devices based on the physical theory of diffraction (PTD). To cope with experimental challenges, particularly for the research in the physical theory of diffraction, an acoustic goniometer must achieve a high enough angular resolution in addition to fulfilling far-field requirements. This paper discusses practical implementations and experimental results of portable goniometers with a radius of up to five meters and an angular resolution of 1.25 degrees. The practical implementation is intended to be easily deployable in empty, indoor spaces of sufficiently large dimensions for scattered reflection characterization. This paper discusses an effort of increasing experimental efficiency of characterization procedures for oblique incidences.

Random incidence absorption characteristics and parameterized design of micro-perforated panel absorbers with parallel-arranged backing cavities at different depths

Micro-perforated panel absorbers (MPAs) are recognized as efficient and environmentally friendly materials for sound absorption, prompting significant research efforts to expand their frequency ranges. This study investigates the acoustic performance of MPAs with parallel-arranged backing cavities at different depths (PCD) under random incidence conditions. Initially, an analytical model is proposed to predict the acoustic performance of PCD-MPA. The model exhibits significant consistency with finite element simulations and experimental measurements, validating its reliability in calculating absorption coefficients within the primary frequency band of concern (500~4000 Hz) in architectural acoustics applications. Subsequently, a thorough discussion of the key parameters, including the depth sequence and perforation parameters, which influence the random incidence absorption characteristics of PCD-MPA is presented based on the proposed model. These discussions lead to the development of an enhanced parameterized design method aimed at improving the absorption performance of PCD-MPA, enabling precise modulation of parameter combinations to meet specific application requirements and design nearly perfect absorbers.

Recycled plastics based impact noise resilient layer development

Sustainability and the carbon footprint reduction is commonly associated with recycling and secondary use of materials, for example also in the building construction industry. For decades, experts have been dealing with this topic across the entire spectrum of the development of building structures. One of the areas where soft recycled materials find suitable application is the area of building acoustics with a focus on impact noise attenuation. This contribution focuses on resilient layers dedicated for lightweight floating floors. This type of flooring is very often used in the reconstruction of apartments in apartment buildings. There is usually no possibility to realize heavy floating floors or for static reasons or reasons of the structural height of rooms or door openings. The work focuses on the development of floor underlayer mats based on recycled material in several variants. These were experimentally compared with conventional materials used in practice as the so-called impact sound insulation layers under laminate floors in terms of improving the impact noise insulation as well as the dynamic stiffness and the loss factor.

Towards better understanding and communication of uncertainty in architectural acoustics and noise control

The fields of architectural acoustics and noise control involve conducting measurements, running analyses, modeling, and making predictions about the behavior of sound in the built environment. Such tasks inherently involve uncertain aspects that affect the reliability of results. This presentation presents a general philosophy around uncertainty with suggestions on how to acknowledge and approach uncertainty, in an effort to move those involved in architectural acoustics and noise control toward better understanding and communication of uncertainty. Terminology, concepts, and pertinent standards that address uncertainty are also reviewed.

Sympathetic resonance of the pipe organ and its effects on concert Hall acoustics

The pipe organ stands present at most every famous concert hall and church sanctuary, yet often it serves only as decoration, rarely played. What effects, then, does the world’s largest class of musical instrument have on the acoustics of concert halls that house them? With prominent metal resonators typically positioned as the immediate back wall of the stage, it is difficult to believe that the pipe organ has little sonic effect, even when it isn’t being played. One hypothesis is that the pipe organ makes for some manner of auto-tune, as its pipes sympathetically resonate to the same frequencies they’re tuned to, thus increasing the amplitude of frequencies that align with well-tuned 12-tone notes, and enhancing the overall musical sound of ensembles that play in concert halls with organs. It was verified experimentally that sympathetic resonance does occur in organ pipes due to musical performance, speeches, and noise, at frequencies that align with musical notes, and that overall amplitude increases when the signal matches the resonance of one or several pipes. Ongoing research is being conducted on the significance of these effects on the overall quality of musical performance to listeners in the audience.

Investigating architectural acoustics modeling with the summer undergraduate research or internship experience in acoustics program

Dante Christian was chosen to participate in an inspiring 10-week experience with the Acoustical Society of America’s Summer Undergraduate Research Experience in Acoustics (SURIEA) Program. Given his physics major and architectural background, SURIEA coordinators felt that he would thrive best as an intern at Acentech (an architectural acoustics firm). The research project that Dante landed on was an auralization of the Warner Theater’s rehearsal room—a structure in Erie, PA. Two of his mentors from Acentech visited to make reverberation time measurements and to ensure that the rehearsal room was behaving as it was intended to. Thus, these measurements came to serve as the backbone of his project’s structure. For Dante’s summer research, he went through the processes of modeling in SketchUp and in Trebel (a geometric and wave-based solver) to gather and simulate impulse responses for the Warner Theater’s Rehearsal room. He worked iteratively to assign absorption and scattering coefficients to the model that best fit the measured experimental results. This is because, especially, absorption coefficients of every material in the room were not specified. Overall, this research project taught Dante how to critically think about a space, its materials, and how its materials interact with the soundscape.

Decarbonizing architectural acoustics: Assessing the CO2 emissions of acoustic systems in an office building in Milan

Nowadays, the Architectural-Engineering-Construction (AEC) market requests buildings with both low CO2 emissions and high performance across all building disciplines, including architectural acoustic systems, to satisfy design regulations and protocols. However, not all acoustic material systems guarantee both of them. Previous research has suggested that design trade-offs exist when reducing CO2 emissions and achieving high-performing room acoustics but a study on a case study is absent. In response, this paper analyses the carbon data set and material quantities of the acoustic systems of a 7-story office building in Milan, Italy. The data are gathered by outsourcing them from the LCA and further analyzed by considering the technical data sheets of the as-built products. The analysis highlights the important role of acoustics in the total amount of CO2 emissions of the building. In particular, horizontal and vertical partitions have the highest impact due to the large material intensities. In conclusion, this research demonstrates that a performance-based LCA analysis is needed to better evaluate the relationship between acoustic performance and CO2 emissions, with future research needed to understand these complex design trade-offs further.

Careers in structural acoustics and vibrations

The structural acoustics and vibrations (SAV) technical committee focuses on research and industry which couple fluid acoustics to structural dynamics. The committee is made up of members from industry, academia, and government whose areas of study cover a wide range of topic areas including but not limited to metamaterials, naval applications, architectural acoustics, and nondestructive evaluation. The training and career paths for those engaged in SAV research and practice is widely varied and this panel discussion will provide insight into the types of careers available which feature SAV. The panel discussion will include panelists Kathryn Matlack (The University of Illinois, Urbana-Champagne), Junfei Li (Purdue University), Amanda Hanford (Applied Research Labs, Penn State University), and Matthew Craun (Naval Surface Warfare Center, Carderock Division). Panelists will answer questions about their careers posed by panel moderators and the audience.

Sound, computers, and all the rest—A career in acoustics

After studying physics and completing his doctorate in 1989 on room acoustic computer simulations, Michael Vorlaender worked from 1989 to 1996 in various areas of acoustics, such as psychoacoustics, electroacoustics and building acoustics at the PTB in Braunschweig. He moved from the position of research officer back to his academic home (“alma mater”) RWTH Aachen University in 1996 and still works there today as Professor of Acoustics. His research focuses on auralization and acoustic virtual reality for perception research and application, particularly in architectural acoustics and noise control. Michael Vorlaender has been involved in several organizations as board member and president. The presentation will give a brief overview of the points at which the career steps included planned or unexpected turning points.

From playing in a high school band room to designing them

Jessica Clements discovered the field of acoustics as a high school senior when a square concrete box was constructed for their new band room. Watching the acousticians moving panels around the room to get the sound the band director wanted illustrated what she’d been looking for in a career – one that captured both music and math. She started her consulting career at Merck & Hill Consultants, with the very acousticians who fixed that HS band room. Over 10 years at Merck & Hill, she performed numerous field measurements and noise control investigations as well as architectural acoustics designs. In 2013, she moved to Newcomb & Boyd, LLP where she spent most of her initial time on mechanical system noise and vibration control design, eventually moving into larger noise control projects related to transportation noise, vibration control, and building acoustic occupant comfort in addition to architectural acoustic design, project management, and business development. She is currently a Principal and the Acoustics Discipline Lead for The Smith Group. This presentation will briefly discuss the trajectory of her career and a few of the key lessons she’s learned.

Designing beyond the acoustical requirements of sustainable design

LEED, WELL, GreenGlobes, and The Living Building Challenge. There are many sustainable design guidelines now being used and developed that include goals related to architectural acoustics and noise control. How can we as consultants bring value to our clients and design partners? Beyond meeting the specifically outlined requirements to achieve points, there are ways we can help our design partners improve the sustainability of the projects. This presentation will review ways to get started on a sustainable design, to start discussions on meeting the specific acoustical goals, and ways to look beyond meeting STC, RT, or NC requirements and bring more to the table.

The building material renaissance: A review of innovative low-carbon, healthy, and acoustically viable building materials

With the pressing need to curb carbon emissions in buildings, architects and designers are increasingly determining low-carbon mitigation strategies across all building disciplines. One solution is the selection of novel low-carbon construction materials, often composed of recycled materials, bio-based products, or wastes. These new building materials are commonly manufactured without harmful chemicals, thereby making the building safer for its occupants. Furthermore, many of the building materials have acoustic benefits, such as improved sound absorption at mid-frequencies. While this new era of building materials encourages low-carbon and healthy buildings, many designers are unaware of them and their advantages. This presentation aims to educate acousticians, designers, and other practitioners by providing a review of innovative building materials (e.g., Pliteq’s GenieMat, fSorb’s Acoustic Panels) that both aid decarbonization efforts and improve building acoustics. An additional outcome of this work is an early version of an open-access dataset of building materials and products for their carbon emissions and acoustic benefit. Overall, this presentation continues the theme of reducing the carbon emissions in the building environment while also considering occupant health and acoustic performance.

ДОСЛІДЖЕННЯ АКУСТИЧНИХ ВЛАСТИВОСТЕЙ ЕЛІПТИЧНОГО (СФЕРИЧНОГО) ГЛУШНИКА ШУМУ

In this work, spherical and hemispherical silencers of exhaust gases of internal combustion engines are consid-ered as separate cases of an elliptical silencer. Spherical and hemispherical mufflers are preferred over elliptical mufflers based on their cheapness and ease of implementation with practically the same acoustic efficiency. The schemes of operation of both of the above silencers were considered: the movement of exhaust gases in them, incoming and reflected sound waves. Assembly drawings of a hemispherical muffler as a special case of an elliptical muffler were also given. An-alytical studies of the acoustic properties of the developed elliptical noise muffler in the low frequency range were carried out. In the high- and medium-frequency frequency ranges, the elliptical muffler suppresses noise due to the effect of sound reflection from the walls of the muffler and returning the latter back to the exhaust pipe. For low-frequency noise, such an effect is practically absent. This type of noise is suppressed in the developed muffler due to the high sound-absorbing properties of the muffler’s inner walls. To determine the effect of noise suppression in the low-frequency range, the laws of architectural acoustics were used, in particular, the reverberation time was calculated for geometric mean frequencies from 125 Hz to 6000 Hz. To ensure high sound-absorbing properties of the internal surfaces of the muf-flers, the use of special glass is proposed. The approximate dependence of the sound absorption coefficient of special glass on frequency is given. In the process of calculating the acoustic efficiency of the muffler, the dependence of the re-verberation time in the muffler on the noise frequency was obtained. At the same time, it was established that the effi-ciency in the area of low frequencies is 30 dB. Keywords: armored car, “Novator”, noise muffler, exhaust gases, acoustics, elliptical muffler, spherical muffler, sound absorption, glass, frequency, acoustic efficiency.