The impact of the acoustic environment on human emotion and experience: A case study of worship spaces

People’s interactions with the environment shape their experiences. Thus, understanding these interactions is critical to enhancing human well-being. Aural attributes play a significant role in shaping the perception of space in addition to visual attributes. It is well known that sounds evoke an emotional response, but less is known about how the acoustic characteristics of environments reinforce such an emotional impact. By adopting virtual reality as a platform for recreating 3D sounds and 360° visuals of built environments of worship spaces as case studies, this study aims to investigate the influence of the acoustic environment considering audiovisual congruency on enhancing the human experience through self-report and physiological response analysis. It also examines the role of cultural background in terms of familiarity with the acoustic environment. The convergent mixed-methods approach, merging both quantitative and qualitative analysis, provides a deep understanding of the role of the acoustic environment in enhancing the auditory experience. The results show that the acoustic environment and audiovisual congruency amplify the intensity of the emotional impact, and the amplification of the impact can vary depending on the acoustic environment of the building. They also reveal that familiarity with sound and acoustic characteristics can increase this impact.

Traffic noise attenuation solutions for naturally ventilated classrooms in South Africa

Traffic noise transmission through the open windows of naturally-ventilated classrooms can reduce speech intelligibility and can negatively impact academic performance. The findings of a numerical study are presented. Software was used to assess effective noise attenuation solutions for naturally-ventilated classrooms exposed to traffic noise. A typical situation in urban schools in Gauteng, South Africa, is considered in which classrooms are ventilated by large open windows in accordance with national building regulations and norms and standards for school design. The aim of the study was to establish a heuristic framework for early design decisions regarding how far from the road a classroom building should be set, and the effective height and position of a solid noise barrier to ensure a suitable ambient noise level inside a classroom with open windows. Efficacy was measured with reference to an indoor ambient sound level of 40 dBA. The findings show that with the insertion of barriers, the required ambient level was achieved for a classroom at least 68 m from the road, if the barrier is at least 3.5 m high. However, it was found that a significant insertion loss (>6 dB) and an improved signal to noise ratio could be achieved for classrooms as close as 17 m from the road with a barrier of at least 2 m high. Though not broadly generalizable, the findings provide a heuristic guide applicable for designing new schools or selecting attenuation interventions in existing city schools that are similar to those used in the study.

The effect of classroom acoustic conditions on literacy outcomes for children in primary school: A review

Literacy skills are essential for success in today’s society. However, classrooms often have suboptimal acoustic conditions for learning. The goal of this review was to synthesize research assessing the effect of different classroom acoustic conditions on children’s literacy. A comprehensive search of four online databases was conducted in August 2021. The search term was classroom AND (noise OR reverberation OR acoustics) AND (reading OR spelling OR writing OR literacy). Eighteen papers were deemed relevant for the review plus an additional seven from their references. The types of acoustic conditions that have been assessed, the types of measures used to assess literacy, and the effect of the acoustic conditions on children’s reading, writing, and spelling outcomes are discussed. Suggestions for the classroom acoustic conditions needed to ensure appropriate literacy development and areas for future research are also considered.

Architectural acoustic design: Observation of use cases including audio-only and multimodal auralizations

Auralization technology has reached a satisfactory level of ecological validity, enabling its use in architectural acoustic design. Only recently have the actual uses of auralization in the consulting community been explored, resulting in the identification of a variety of uses, including (1) to present to clients, (2) to test design ideas, (3) as a verification tool, (4) as a verification tool, (5) as a marketing tool, and (6) to improve internal company discussions. Taking advantage of methodologies from ergonomics research, the present study investigates effective uses through the observation of a collaboration project between an acoustic research team and an acoustic consultant, as a case study. Two spaces have been auralized in the context of the conception of a new skyscraper during the design phase of the project. The two spaces faced different problematics: an Atrium for which three different acoustic treatment options were suggested and experienced through multi-modal auralizations and audio-only auralizations of an Auditorium where an intrusive noise was to be acoustically treated. The ergonomic observation and analysis of this project revealed key impediments to the integration of auralization in common acoustic design practices.

An ultra-thin multi-layered metamaterial for power transformer noise absorption

A compact multi-layered structure is proposed based on the coiled-up space concept for power transformer noise absorption at 100 and 200 Hz. Current methods of constructing multi-band absorbers are impractical for power transformer noise control due to the high coupling effect deteriorating their performance. To overcome this shortcoming, the proposed structure is composed of multiple connected layers creating two separate coiled ducts with adjustable dimensions to minimise the coupling effect. In the modelling stage, the geometrical features are optimised using the genetic algorithm to maximise the absorption coefficient and minimise the thickness. The proposed dual-tone absorber has a thickness of 43.5 mm which is significantly thinner than the existing conventional absorbers. The measurement results on a 3D-printed structure demonstrate the feasibility of the design.

Acoustics in South African classrooms: Regulations versus reality

This research set out to broaden the pool of evidence regarding the acoustic conditions at schools in South Africa. A review of local and international literature, standards and design guidelines shows that the ideal classroom acoustic conditions of 35 dBA ambient and 0.7 s reverberation time are required to enable a suitable environment for teaching and learning. A review of local literature revealed a very small body of knowledge regarding actual acoustic conditions and monitoring of classroom acoustics and that these cases demonstrated ambient noise levels in classrooms (whether occupied or unoccupied) to be above the recommendations of the relevant South African National Standard (SANS 10103). The limited local research promted the need for this case study. The findings of a province-wide survey of urban schools showed that traffic noise is the main source of noise disturbance in schools. A case study of five schools showed that the average outdoor noise level at schools exposed to traffic throughout the day is 63.3 dBA and the average indoor noise level at these schools when classrooms are unoccupied is approximately 58 dBA, which is significantly higher than the requirement. The reverberation time in classrooms was between 0.6 and 1.75 s. It is concluded that the current acoustic conditions in South African urban schools is poor when evaluated against the South African National Standards. However, since this is based on only five case studies, a broader study is required to understand the general conditions and establish suitable mitigation measures.

Sound predictions in an urban context

Recent studies show that environmental noise in urban environments continues to be a great health risk. This noise is especially further transmitted by the hard materials that are mostly used for façades. To predict these effects it is desirable to have a reliable prediction method. There are already several ways to predict sound levels in an urban context. This paper investigates two while focusing specifically on a practical approach to show that the methods are suitable to use during an actual design project. The impact of changing a façade at a specific location is investigated using both prediction methods. A façade which reflects sound to a location where it has a smaller impact, a sound absorbing façade, and a façade which combines both are taken into consideration. These façade adaptions have the potential to improve the sound levels in the investigated area from 1.7 up to 9.3 dB(A).

A critical review of acoustic modeling and research on building façade

Noise pollution has been impacting negatively on living comfort and working environment for a long time. Acoustic treatment on building façade is one of the effective means to tackle this issue. Numerous articles were published over the past decades to address the acoustic related problems of building façade. However, a systematic review of the research development on façade acoustic technology is lacking. Therefore, this paper examines the published research articles from seven selected journals, in terms of the annual number of articles, citation counts, co-authorships, research locations, and keywords. The analyses show that interest in façade acoustics increased during the last two decades. Researchers from Europe and areas with a high density of tall buildings made significant contributions to this development. Based on keyword analysis, articles are categorized into three groups. These include sound insulation studies, studies on the effect of façade on street noise, and noise reduction techniques. The surveyed research topics comprise numerical modeling, experimental studies, ISO standard development, and analyses on annoyance level. Potential future directions are presented based on a summary of the limitations of the existing research. This paper offers researchers and engineers an in-depth understanding of the state-of-the-art of the current façade acoustic research. Additionally, potential future directions are identified based on the findings and limitations of the previous studies.

Preliminary rolling noise measurements toward the design of a standard rolling noise device

The tapping machine has long existed as the primary standard method for measuring the performance of floors in buildings in response to structure-borne noise. However, other sources of structure-borne noise exist. One of these is rolling noise: such as a trolley rolling across the floor in an indoor building environment. Because the sound profile of indoor rolling noise is substantially different than that of impact noise, the techniques developed to reduce the latter may not necessarily be effective at reducing the former. To this end, a means of repeatably measuring indoor rolling noise is needed. Here the results of a study on indoor rolling noise are presented, identifying the various characteristics of this type of excitation which until now have been left unexplored. The proposal for a standard rolling device is also put forth: a machine which may be capable of characterizing a floor’s performance with regards to indoor rolling noise. A series of indoor rolling noise tests were conducted in order to characterize the range of sound profiles that various indoor rolling items are capable of producing, as well as identify how the different characteristics govern the shape of the sound profile produced. Just as the standard tapping machine assesses a floor’s performance in response to impact noise, a standard rolling machine may assess a floor’s performance in response to rolling noise.

Experimental study on the insertion loss of multilayer panels featuring a periodic structure

Acoustic panels with different configurations (layered structure with different absorbing materials) are broadly used to attenuate the noise. Multiple panels are preferred due to the presence of multiple air cavities and the repeated reflections which lead to increased sound attenuation. The paper presents an experimental study of sound propagation through multiple panels. A novel design of acoustic panel is proposed by incorporating the sonic crystal in the air cavities of the panel. Sonic crystal (SC) consists of a periodic arrangement of sound hard scatterers which provide the sound reduction in a particular frequency range due to destructive interference in periodic scatterers. The results are based on experimental observations which are supported by the literature. The results show that increasing the number of panels increases the sound insertion loss from the multiple panel structure. However, the panels with air cavity suffer from the sound insertion loss dip, which makes the panel ineffective. The novel acoustic panel (double and triple panel with SC) provides an additional sound reduction due to SC which can be tailored for certain frequency band. For the present case, SC is designed to overcome the insertion loss dip. The novel panel provides an additional insertion loss, reaching a maximum value of 19 and 11 dB, respectively (for the double and triple panel), overcoming the insertion loss dip due to structural vibration.