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Informed by acoustic design standards, the built environments are designed with single reverberation times (RTs), a trade-off between long and short RTs needed for different space functions. The novel intelligent passive room acoustic technology (IPRAT) has the potential to revolutionise room acoustics, thus, it is imperative to analyse and quantify its effect. IPRAT achieves real-time room acoustic improvement by integrating passive variable acoustic technology (PVAT) and acoustic scene classification (ASC). This paper aims to compare IPRAT simulation results with the AS/NZS 2107:2016 Australian/New Zealand recommended design acoustic standards.

In this paper 20 classroom environments are virtually configured for the simulation, multiplying 5 classrooms with 4 aural situations typical to New Zealand classrooms. The acoustic parameters RT, sound clarity (C50) and sound strength (G) are considered and analysed in the simulation. These parameters can be used to determine the effects of improved acoustics for both teacher vocal relief and student comprehension. The IPRAT was assumed to vary RT and was represented in the simulation by six different absorption coefficient spectrums.

The optimised acoustic parameters were derived from relationships between C50, RT and G. These relationships and optimal RTs contribute a unique database to literature. IPRAT’s advantages were discerned from a comparison of “current,” “attainable” and “optimised” acoustic parameters.

By quantifying the effect of IPRAT, it is understood that IPRAT has the potential to satisfy the key recommendations of professional industry standards (for New Zealand namely; AS/NZS 2107:2016 recommended design acoustic standards).

Informed by acoustic design standards, the built environments are designed with single reverberation times (RTs), a trade-off between long and short RTs needed for different space functions. A range of RTs should be achievable in spaces to optimise the acoustic comfort in different aural situations. This paper proclaims a novel concept: Intelligent passive room acoustic technology (IPRAT), which achieves real-time room acoustic optimisation through the integration of passive variable acoustic technology (PVAT) and acoustic scene classification (ASC). ASC can intelligently identify changing aural situations, and PVAT can physically vary the RT.

A qualitative best-evidence synthesis method is used to review the available literature on PVAT and ASC.

First, it is highlighted that dynamic spaces should be designed with varying RTs. The review then exposes a gap of intelligently adjusting RT according to changing building function. A solution is found: IPRAT, which integrates PVAT and ASC to uniquely fill this literature gap.

The development, functionality, benefits and challenges of IPRAT offer a holistic understanding of the state-of-the-art IPRAT, and a use case example is provided. Going forward, it is concluded that IPRAT can be prototyped and its impact on acoustic comfort can be quantified.

As oral communication in higher education is vital, good classroom acoustics is needed to pass the verbal message to university students. Non-auditory factors such as academic language, a non-native educational context and a diversity of acoustic settings in different types of classrooms affect speech understanding and performance of students. The purpose of this study is to find out whether the acoustic properties of the higher educational teaching contexts meet the recommended reference levels.

Background noise levels and the Speech Transmission Index (STI) were assessed in 45 unoccupied university classrooms (15 lecture halls, 16 regular classrooms and 14 skills laboratories).

The findings of this study indicate that 41 classrooms surpassed the maximum reference level for background noise of 35 dB(A) and 17 exceeded the reference level of 40 dB(A). At five-meter distance facing the speaker, six classrooms indicated excellent speech intelligibility, while at more representative listening positions, none of the classrooms indicated excellent speech intelligibility. As the acoustic characteristics in a majority of the classrooms exceeded the available reference levels, speech intelligibility was likely to be insufficient.

This study seeks to assess the acoustics in academic classrooms against the available acoustic reference levels. Non-acoustic factors, such as academic language complexity and (non-)nativeness of the students and teaching staff, put higher cognitive demands upon listeners in higher education and need to be taken into account when using them in daily practice for regular students and students with language/hearing disabilities in particular.

To maximise acoustic comfort in a classroom, the acoustic conditions of the space should be variable. So, the optimal acoustic state also changes when the classroom changes from a study environment into a lecture environment. Passive Variable Acoustic Technology (PVAT) alters a room’s Reverberation Time (RT) by changing the total sound absorption in a room. The purpose of this paper is to evaluate the improvements to classroom acoustic comfort when using PVAT.

The study is conducted in an existing tertiary classroom at Auckland University of Technology, New Zealand. The PVAT is prototyped, and the RTs are measured according to international standards before and after classroom installation. The acoustic measurement method used is a cost-effective application tool where pre- and post-conditions are of primary concern.

PVAT is found to offer statistically significant improvements in RT, but the key benefits are realised in its’ ability to vary RT for different classroom situations. It is predicted that the RT recommendations for two room types outlined in the acoustic standard AS/NZS 2107:2016 are satisfied when using PVAT in a single classroom space. By optimising RT, the acoustic comfort during both study and lecture is significantly improved.

When PVAT is combined with an intelligent system – Intelligent Passive Room Acoustic Technology (IPRAT) – it can detect sound waves in real time to identify the optimal RT. This paper details a pilot case study that works towards quantifying the benefits of IPRAT, by prototyping and testing the PVAT component of the system.

1. A pilot case study outlines the development and test of a variable acoustic prototype in a tertiary classroom

2. A method is adopted to measure acoustic conditions, using three under-researched Android applications

3. The benefits of PVAT are realised in its ability to vary RT by adjusting the prototypes’ sound absorption

4. By using PVAT in a single space, the recommended RTs for two room types outlined in the acoustic standard AS/NZS 2107:2016 can be satisfied

5. The improvements in acoustic comfort due to PVAT are statistically significant

A pilot case study outlines the development and test of a variable acoustic prototype in a tertiary classroom

A method is adopted to measure acoustic conditions, using three under-researched Android applications

The benefits of PVAT are realised in its ability to vary RT by adjusting the prototypes’ sound absorption

By using PVAT in a single space, the recommended RTs for two room types outlined in the acoustic standard AS/NZS 2107:2016 can be satisfied

The improvements in acoustic comfort due to PVAT are statistically significant

Mosques 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.

The 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.

The 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.

This 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.

A recently developed calculation scheme for the numerical computation of the load‐controlled acoustic noise of power transformers is presented. This modeling scheme allows the precise and efficient computation of the coupled electromagnetic, mechanical and acoustic fields. The equations are solved using the finite element method (FEM) as well as the boundary element method (BEM), resulting in a separation of the acoustic‐magnetomechanical calculation of the winding vibrations resp. the acoustic‐mechanical computation of the tank vibrations (using FEM) and the calculation of the acoustic free‐field radiation (using BEM). The validity of the computer simulations has been verified by means of appropriate measurements. Simulated and measured values for winding and tank surface vibrations as well as the sound power level of the loaded transformer are found to be in good agreement.

The purpose of this paper is to examine the use of a new feature reduction technique with novelty detection on vibration and acoustic‐emission sensors monitoring bearings mounted in the test benches of automotive manufacturers.

Signals from standard accelerometers and acoustic‐emission sensors were gathered from bearings operating under steady conditions on an accessory‐drive test bench. The bearings under test were subject to a variety of faults including fretting. These signals were processed and reduced to standard feature vectors, the dimensionality of which was reduced using a new principal‐component‐like technique optimized for novelty detection. The reduced data were analyzed with a novelty detection technique called the Support Vector Data Descriptor.

The classification results from these sensors, after being reduced with the proposed feature reduction technique, are substantially improved over those achievable with only standard novelty detection; nearly zero‐percent classification error was achieved.

The feature reduction technique depends, in part, on the availability of the fault type in question – potentially violating the normal novelty detection assumption of limited abnormal data. This may require the manufacturer to gather real or simulated fault data prior to running tests.

Incipient faults may be detectable at a much earlier stage in a manufacturer's component failure analysis. Test engineers may use this technique to reliably automate the fault detection process and enable improved root‐cause analysis through the earlier identification of faults.

The application of the feature reduction technique will provide manufacturers and researchers with a new means of improving fault detection in machinery components.

Ciliated microelectromechanical system (MEMS) vector hydrophones pick up sound signals through Wheatstone bridge in cross beam-ciliated microstructures to achieve information transmission. This paper aims to overcome the complexity and variability of the marine environment and achieve accurate location of targets. In this paper, a new method for ocean noise denoising based on improved complete ensemble empirical mode decomposition with adaptive noise combined with wavelet threshold processing method (CEEMDAN-WT) is proposed.

Based on the CEEMDAN-WT method, the signal is decomposed into different intrinsic mode functions (IMFs), and relevant parameters are selected to obtain IMF denoised signals through WT method for the noisy mode components with low sample entropy. The final pure signal is obtained by reconstructing the unprocessed mode components and the denoising component, effectively separating the signal from the wave interference.

The three methods of empirical mode decomposition (EMD), ensemble empirical mode decomposition (EEMD) and CEEMDAN are compared and analyzed by simulation. The simulation results show that the CEEMDAN method has higher signal-to-noise ratio and smaller reconstruction error than EMD and EEMD. The feasibility and practicability of the combined denoising method are verified by indoor and outdoor experiments, and the underwater acoustic experiment data after processing are combined beams. The problem of blurry left and right sides is solved, and the high precision orientation of the target is realized.

This algorithm provides a theoretical basis for MEMS hydrophones to achieve accurate target positioning in the ocean, and can be applied to the hardware design of sonobuoys, which is widely used in various underwater acoustic work.

Personal lifestyle, work environments and work-related factors can significantly affect occupant productivity. Although many studies examine the affecting factors of occupant productivity in offices, explorations for the home-based work environment, which is designed mainly for living purposes, are still scarce. Moreover, current pandemic has made work from home a new normal for workers around the world. Therefore, it is important to identify key causal factors of occupant productivity when working from home.

This study employed descriptive analysis and regression analysis method to explore the relationship among personal lifestyle, indoor environmental quality and work-related factors toward occupant productivity. A questionnaire including a comprehensive list of key measures was designed and 189 valid responses were collected from more than 13,000 participants.

Results show that a healthy lifestyle, the perceived satisfaction of visual and acoustic environment, communication, interest in work, workload, flexible schedule and privacy positively affect occupant productivity when working from home, while coffee consumption, outside views and windows have negative effect.

Opportunities to enhance occupants' home-based work productivity include developing a healthy lifestyle by taking advantage of flexible schedule, equipping a working room at home with advanced and intelligent environment control systems, and improving communication, workload and schedule by changing the policy of companies.

With a push toward inclusion of students with disabilities in the general education classroom, students who are d/Deaf or hard of hearing (DHH) are exposed to greater educational opportunities. Given the largely verbal nature of traditional classroom instruction, there has been a need for advancements in technology to provide more access to the material covered by teachers and in class discussions. In addition, the COVID-19 pandemic and the transition to virtual learning also brought to light many additional challenges for the DHH population, which can, in part, be lessened through technological advancements.