Architectural Acoustics Research Articles

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from the former state of Yugoslavia were left in effect and have remained in use even after they were officially withdrawn, as no new regulations were adopted to replace them.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.

Ten questions concerning Architectural Acoustics

Building and room acoustics are relatively modern architectural and engineering disciplines. Nevertheless, acoustics was also a concern for buildings in the past, e.g., in theatres in ancient Greece and in Roman times. Nowadays, we spend 80–90 % of our time indoors, and sound impacts our communication and actions in an environment to a great extent. Therefore, acoustic aspects should be considered appropriately in the Environmental Quality and Global Comfort context as part of the overall aspects of building physics, although other factors (e.g., thermal, air quality, etc.) are conventionally considered more “mainstream”. The ten questions considered in this paper range from the basic definitions underlying the differences between building and room acoustics, to more applied topics about how to measure, simulate and use acoustic data in the design of the built environment. Significant research activities have been conducted by acoustic experts on different aspects related to the measurements of physical properties, perceptual aspects and technological development in both the physical and virtual dimensions, thereby paving the way towards a more inclusive and healthier acoustic environment. Apart from illustrating the current state of the art, the answers to these questions point out the still existing gaps in the field and future challenges, thereby highlighting the new competencies required to support the design of the acoustic environment, focusing on the physical, physiological, and psychological needs of the users.

The Historical Building and Room Acoustics of the Stockholm Public Library (1925–28, 1931–32)

The Stockholm Public Library was realized in two distinct phases of construction in the 1920s and early 1930s, and remains a well-known work in twentieth-century architecture, with a heritage status today. While previous studies have focused on the library’s architectural design, particularly its lighting, acoustics were also an important aspect of the building’s design and construction. This study marks the first detailed investigation of the library’s architectural acoustics, with a suite of standard measurements performed to assess and characterize the library’s historical room and building acoustics. Reverberation time measurements in the library’s reading rooms yielded results of about 1.5–2 s for frequencies associated with speech. A significantly longer reverberation time of 5–6 s was measured in the library’s central rotunda, confirming a prominent acoustic issue in the library, where appropriate heritage discussions are needed in the future as the library undergoes a major renovation in the coming years. A comparison of the measured airborne and impact sound insulation of the 1920s and 1930s reading room ceilings also yielded interesting results. While the materials in library’s two construction periods are notably different, the airborne sound insulation performance of the 1920s and 1930s floors or ceilings was comparable and in line with contemporary standards. Impact sound insulation results from the 1920s and 1930s floors, however, differed significantly, with the latter displaying a relatively poor performance. Flanking transmission effects related to historical construction details and deviations from archival plans were investigated and discussed. This work emphasizes the practical and academic importance of conducting on-site measurements, and the close mutual development of modern architecture, construction, and architectural acoustics.

Speech intelligibility evaluation of small-scale mosque with multiple domes design

PurposeMosques are built with dome-shaped ceilings for communal worship with common architectural styles worldwide for prayer. Since the acoustics of worship buildings are just as significant as their aesthetics, they should enhance people’s sense of hearing. This study evaluates the speech intelligibility of a small mosque with multiple domes to determine the space acoustic conditions.Design/methodology/approachThe investigation involved extensive literature reviews to collect relevant data to model the case study. The Enhanced Acoustics Simulator for Engineers (EASE) software program was used to integrate critical parameters such as the absorption coefficient of materials, dome shapes and the number of domes in the simulation. The study employed speech intelligibility parameters such as C50, S.T.I. and %ALcons to assess the acoustic conditions. The assessment model was validated through statistical analysis and a paired t-test.FindingsThe study discovered that varying shapes of the multiple domes showed no significant impact on speech intelligibility. However, different multiple domes materials resulted in significant disparities in speech intelligibility. Applying high-absorption materials in multiple dome designs achieved the most effective acoustic performance. Except for C50 in some circumstances and receiver positions, all other alternatives met the optimal value for overall speech intelligibility because the sound was not sufficiently diffused early on, suggesting that the early reflection sounds were either weak or insufficient.Originality/valueThis study not only helps to determine the multiple-dome effect on mosque acoustics but also empowers archaeoacoustics and historic conservation by documenting these significant places of worship. The findings advocate using high-absorption materials in multiple dome designs and offer practical insight into mosque design material selection. By enhancing the understanding of the acoustic conditions in small-scale mosques, this study equips architects, engineers and builders with the knowledge to create spaces prioritizing speech clarity and intelligibility.

Application of Cellulose and Paper-Based Products in Building Acoustics

This article presents a comprehensive acoustic study of paper-based building products: cellulose wool, paperboard, corrugated cardboard, and honeycomb panels. The material configurations included the intact form as well as the various modifications, i.e., density variation, multiple-layered staking, perforation or acoustic metamaterial setup. Tests covered acoustic absorption and insulation properties, with the last examined under excitation of both a plane wave and a diffused field. Additionally, the cellulose wool is provided with the characteristic impedance and propagation wavenumber results; and the paperboard was tested for its dynamic elastic and damping properties. The paper-based products, giving their weight, prove to be a convincing replacement for conventional materials by both absorptive and insulation performance. The maximum acquired sound reduction index, for exceptionally lightweight (2.2 kg/m2) paper double-wall metamaterial structure, reached 26 dB.

Tube Dissipation estimation for the Transfer function method using Bayesian inference

Impedance tube measurement is commonly used in material research and building acoustics to study the acoustic properties of materials. However, air dissipation caused by multiple effects affects the accuracy of measurement results. This work discusses sound dissipation due to different effects in an impedance tube. The air layer method is used to measure the dissipation and to calibrate the tube. Accurate dissipation due to different effects is estimated by model-based Bayesian inference. The Bayesian analysis demonstrates the impact of tube dissipation on the acoustic measurements. The estimated tube dissipation drastically improves the accuracy of regular two-mic impedance tube measurements.

Spatially characterized pseudo-perfect diffuseness via finite-degree spherical harmonic diffuseness.

Perfectly diffuse sound fields play an important role in architectural acoustics and there are established theoretical characterizations of perfect diffuseness. Although sound fields in real rooms are diffuse to some extent, they are not perfectly diffuse, and therefore theories are required to describe pseudo-perfectly diffuse sound fields. Here, we aim to spatially characterize pseudo-perfect diffuseness via directional characterization of that, finite-degree spherical harmonic diffuseness. Our results show that finite-degree diffuse sound fields yield local spatial diffuseness, suggesting that spatial pseudo-perfect diffuseness is characterized using the effective radius of diffuseness.

Integration of Acoustic Metamaterials Made of Plastic to Improve Building Acoustics

According to the Waste Management Policy of the European Union, the recycling and reuse of various wastes is considered the most environmentally friendly and advanced waste disposal technology that has the least impact on the environment. By applying the principles of the Circular Economy, plastic waste will extend its life cycle and will be used as secondary materials to create metamaterial structures with improved sound absorption and insulation properties. Acoustic metamaterial resonators, created from plastic, were measured in an impedance tube according to standards ISO 10534-2 for their sound absorbing and ASTM E2611 for their insulating properties. Two types of plastic, PLA and recycled PET-G, were used in acoustic metamaterial 3D printing process. Sound absorption of both PLA and PET-G metamaterials were peaking at 1600 Hz with 0,93 and 0,89 sound absorption coefficient, respectfully. For sound insulation, combined resonator systems were used to control symmetrical wall sound resonance. The aim of this study was to determine plastic potential for use in acoustic structures. The results showed that combined constructions with plastic metamaterials can be integrated into building structures and used as an alternative for improving building acoustics, reducing indoor noise and reverberation time.

The calibration device research for assessing the impact exposure level of rubber balls in architectural acoustics

In order to accurately measure the impact exposure level of rubber balls used in architectural acoustics, a calibration device is designed based on a force sensor, signal analyzer, programmable stepper motor and Infinite Impulse Response (IIR) filter. A weighing sensor with a range of 200 kg is selected to match the range of impact forces of rubber balls. The sensor is installed on a specially designed metal base plate of a rubber ball measuring fixture and connected to the signal analyzer. The rubber ball is dropped from a predetermined height in a free-fall manner to impact the sensor, generating an impact waveform. The force exposure level is then calculated by using software algorithms built into the device. The accuracy and reliability of the calibration device are evaluated by conducting repeated measurements on rubber balls and comparing the results with a known standard force exposure level curve. The experimental results demonstrate that the calibration device can consistently and stably measure the force exposure level of rubber balls, showing consistency with the known standard values. However, due to limitations such as a limited variety of measured objects and insufficient measurement repetitions, further research will be conducted to increase the number of tested rubber balls and enhance the device’s capabilities. This will provide technical support for the further development and application of the device.

Architectural acoustics: Buildings and beyond

Architectural acoustics not only covers buildings and the environment around them but also human perception of the acoustic environment, indoors and outdoors. As a technical committee of the acoustical society, our members are spread over research, academia, practitioners and industry. Architectural acoustics is not reserved for concert halls and opera houses but applies to all occupied spaces and has a direct impact on quality of life of any user of the space. Specific topics within the discipline include but are not limited to environmental sound, speech privacy, and speech intelligibility, simulated acoustic environments, annoyance, human hearing, airborne and structureborne noise, sound and impact isolation, loudspeakers and microphones, room acoustics, soundscape, and acoustical measurements. The technical committee on noise is often a cosponsor of specials sessions by the TCAA, as noise control via architectural means is common practice. This presentation will provide an overview of the TCAA and the field of architectural acoustics and provide examples of current research and projects of interest.

The Graduate Program in Acoustics at Penn State

The Graduate Program in Acoustics at Penn State offers graduate degrees (M.Eng., M.S., Ph.D.) in Acoustics, with courses and research opportunities in a wide variety of subfields. Our 820 alumni are employed around the world in military and government labs, academic institutions, consulting firms, and consumer audio and related industries. Our 40 + faculty from several disciplines conduct research and teach courses in structural acoustics, nonlinear acoustics, architectural acoustics, signal processing, aeroacoustics, biomedical ultrasound, transducers, computational acoustics, noise and vibration control, acoustic metamaterials, psychoacoustics, and underwater acoustics. Course offerings include fundamentals of acoustics and vibration, electroacoustic transducers, signal processing, acoustics in fluid media, sound and structure interaction, digital signal processing, experimental techniques, acoustic measurements and data analysis, ocean acoustics, architectural acoustics, noise control engineering, nonlinear acoustics, outdoor sound propagation, computational acoustics, biomedical ultrasound, flow induced noise, spatial sound and three-dimensional audio, and the acoustics of musical instruments. Distance education students pursuing the M.Eng. degree join resident students in a hybrid classroom environment. This poster highlights faculty research areas, laboratory facilities, student demographics, successful graduates, and recent enrollment and employment trends.

Architectural acoustics continuing education course—Presenter registration and reporting

The Technical Committee on Architectural Acoustics (TCAA) is a Registered Provider in the American Institute of Architects (AIA) Continuing Education System (CES). The TCAA has developed a standardized introductory short course for architects called “Architectural Acoustics,” for which attendees can earn one continuing education unit (CEU). This paper will cover the administrative requirements of the ASA/CES, to prepare potential presenters. These requirements include the proper handling of paperwork so that AIA members may receive credit for the course. The manner in which the course is given is also dictated by AIA requirements. TCAA membership and attendance at this workshop are required to qualify as an authorized presenter for this AIA/CES short course. Of course, anyone is free to register with the AIA to provide their own CEU program. However, the advantages of participating in this program are that the TCAA short course is already prepared, it is pre-approved by the AIA, and the registration fees are paid by the Acoustical Society of America.

Architectural acoustics short course presentation material

The Technical Committee on Architectural Acoustics (TCAA) is a Registered Provider in the American Institute of Architects (AIA) Continuing Education System (CES). The TCAA has developed a standardized introductory short course for architects called “Architectural Acoustics,” An architect can earn one continuing education unit (CEU) by attending this short course, if presented by a qualified member of TCAA. The course covers topics in sound isolation, mechanical system noise control, finish treatments, and implementation of quality acoustical spaces. This paper will cover the course material in order to prepare and qualify potential presenters. In order to qualify as an authorized presenter for this AIA/CES short course, attendance at this special session and membership in TCAA are required.

Advancement of the exterior façade measurement method by Jerry Christoff

Acoustical design of façade elements is a key element in architectural acoustics. The assessment is required for multi-family housing projects and environmental projects. In the 1980s, when labs around the US were measuring the transmission loss (TL) of exterior façade elements, it was assumed that measurement of TL with a diffuse sound field method is valid for TL of real facades where a diffuse sound field does not exist. Jerry evaluated how the TL of exterior façade elements change based on the incident angle. In this talk, we will shed some light on the history of the work done by Jerry in the advancement of the exterior façade assessment methods.

Simulation of acoustical parameters of churches in a virtual acoustics laboratory

Current ISO standards for acoustical assessment limit the use of traditional mono-dimensional microphones for measuring equipment. However, microphone arrays offer more accurate spatial information compared to traditional microphones. This presents an opportunity to enhance research on architectural acoustics and preserve the acoustics of cultural heritage more effectively. Furthermore, modern recording studios equipped with virtual acoustics systems allow for the integration of spatial room impulse responses. This enables real-time auralization in controlled environments and enhances the overall immersive audio experience for users and musicians. This paper analyzes the main acoustical parameters obtained from spatial impulse responses captured in churches using various ambisonic microphones and inserted into a controlled, interactive, and immersive virtual acoustics system. The captured spatial acoustic measurements are then reproduced and evaluated in a virtual acoustics laboratory to identify any discrepancies between real and virtual spaces.