Subjective Experience of Speech Depending on the Acoustic Treatment in an Ordinary Room

In environments such as classrooms and offices, complex tasks are performed. A satisfactory acoustic environment is critical for the performance of such tasks. To ensure a good acoustic environment, the right acoustic treatment must be used. The relation between different room acoustic treatments and how they affect speech perception in these types of rooms is not yet fully understood. In this study, speech perception was evaluated for three different configurations using absorbers and diffusers. Twenty-nine participants reported on their subjective experience of speech in respect of different configurations in different positions in a room. They judged sound quality and attributes related to speech perception. In addition, the jury members ranked the different acoustic environments. The subjective experience was related to the different room acoustic treatments and the room acoustic parameters of speech clarity, reverberation time and sound strength. It was found that people, on average, rated treatments with a high degree of absorption as best. This configuration had the highest speech clarity value and lowest values for reverberation time and sound strength. The perceived sound quality could be correlated to speech clarity, while attributes related to speech perception had the strongest association with reverberation time.

Multi-objective building design optimisation using acoustics and daylighting

Daylighting and acoustics parameters are related to each other in terms of material usage, specifically for window openings. However, no study has included acoustics and daylighting as objectives in the multi-objective optimisation models. In this study, this relationship was included to the optimisation process of generating building conceptual form. A model was developed to optimise the form of a building using acoustics, daylighting and floor area as the objectives. Daylight autonomy parameter for daylighting performance and C50 (speech clarity), reverberation time, Speech Transmission Index parameters for acoustic performance were used in the model which was created with visual programming language. Case studies were conducted with the model, and the results were discussed. Maximising speech clarity and maximising annual daylighting in the space were determined as objectives for the building form optimisation process in the case studies.

Re-evaluation acoustic quality in lecture halls using G and C50: University of Sharjah Case Study

In our previous studies, we focused on the common approach of measuring Reverberation Time (RT) for assessing acoustic quality in various types of lecture halls at the University of Sharjah (United Arab Emirates). The absorbing surfaces at the lecture halls at the University of Sharjah are limited to one surface (hanging ceiling), which has been shown in the literature to affect the accuracy in the description of the acoustic response as a result of the introduced uncertainty in the measured reverberation times. Because of these reasons, it has been highlighted in the literature that RT is considered not a good predictor of acoustic quality, namely speech intelligibility, in the lecture halls. Therefore, additional acoustic parameters need to be measured of calculated to accurately predict the acoustic response in lecture halls, especially speech intelligibility during activities that takes place within the lecture hall. The focus of our current research is to extend our precious work on RT to calculate additional acoustic parameters, namely the acoustic strength, G, and the speech clarity, C. Our goal is to investigate the practical use of G and C to describe acoustic response in the examined lecture halls. In addition to special variations with frequency, we will examine the effects source position, room dimensions at different locations within the lecture hall. The measurements were conducted in the same lecture halls under the same conditions including the acoustic absorbers and sound diffusers, which have shown to influence measured acoustic parameters. The results were compared to standards for the purpose of providing recommendations for range of acoustic parameters to support adequate speech communication during various teaching and learning activities in lecture halls.

Development of Folded Expanded Metal Mesh with Sound Absorption Performance

Reverberation time (RT) is an important factor affecting the quality of indoor acoustics. Using sound-absorbing materials is one method for quickly and effectively controlling RT, and installation in the ceiling is a common location. Sound-absorbing ceilings come in many forms, with light steel joist ceilings commonly used in office spaces, classrooms, and discussion rooms. Light steel joist ceilings are often matched with sound-absorbing materials such as gypsum board, mineral fiberboard, rock wool, and coated glass wool, but such materials may have durability and exfoliation problems. Therefore, considering performance and health, in this research, we aimed to design an expanded metal mesh (EMM) structure specimen for sound-absorption material, namely folded expanded metal mesh (FEMM). The results show that the FEMM can significantly improve the sound-absorption performance of the expanded metal mesh. Theof single panel is 0.05–0.35, and theof FEMM is 0.65–0.85. On the other hand, the sound-absorption performance of the full frequency band has been significantly improved. Furthermore, the field validation result shows that RT decreased from 1.05–0.56 s at 500 Hz, meanwhile, the sound pressure level (SPL) is still evenly distributed, and speech clarity (C50) is increased by 5.6–6.5.

Perceptual and Acoustic Characteristics of Speech Clarity with and Without a Facemask

Some studies have found that the speech of speakers wearing facemasks has reduced intelligibility. Although it has been found that facemasks attenuated high-frequency energy, no study has examined the effects of masks on spectral characteristics of vowels or voiceless fricative consonants. The present study investigated auditory perceptual rating of speech clarity and acoustic-phonetic measures of vowels and voiceless fricative consonant production in 16 health care workers who produced standardized voice tasks without and with wearing either a standard surgical mask or a KN95 mask. Voice samples were perceptually rated for speech clarity and were acoustically analysed for root-mean-square amplitude (ARMS), spectral moments of two voiceless fricatives /s/ and /ʃ/, and ARMS and amplitude of the first three formants (A1, A2, and A3). Speech produced whilst wearing either a surgical or KN95 mask was significantly less clear than without a mask, with KN95 showing greater impact than surgical masks. In both fricatives, ARMS was lower in the surgical mask and KN95 mask conditions compared to the non-mask condition. None of the amplitude measures of vowels were affected by facemasks. Linear regression models indicated that perception of speech produced by mask users was mainly affected by modification of voiceless fricative consonant characteristics.

Deep Neural Network Based Noised Asian Speech Enhancement and Its Implementation on a Hearing Aid App

This article studies noised Asian speech enhancement based on the deep neural network (DNN) and its implementation on an app. We use the THCHS-30 speech dataset and the common noise dataset in daily life as training and testing data of the DNN. To stack the frequency data of multiple audio frames to improve the effect of speech enhancement, the system compares the best number of stacked frames during training and testing. At the same time, the influence of training rounds on the PESQ is compared, and the best number of rounds is obtained. On this basis, the best model is implemented on the hearing aid app, and the real-time performance of the device is tested. The experiment shows that based on the DNN, using an appropriate number of rounds for training and using an appropriate number of audio frames stacking to improve the speech enhancement effect, and transplanting this speech enhancement model to the hearing aid app, can effectively improve speech clarity and intelligibility within a reasonable time delay range.

An Energy Model for the Calculation of Room Acoustic Parameters in Rectangular Rooms with Absorbent Ceilings

The most common acoustical treatment of public rooms, such as schools, offices, and healthcare premises, is a suspended absorbent ceiling. The non-uniform distribution of the absorbent material, as well as the influence of sound-scattering objects such as furniture or other interior equipment, has to be taken into account when calculating room acoustic parameters. This requires additional information than what is already inherent in the statistical absorption coefficients and equivalent absorption areas provided by the reverberation chamber method ISO 354. Furthermore, the classical diffuse field assumption cannot be expected to be valid in these types of rooms. The non-isotropic sound field has to be considered. In this paper, a statistical energy analysis (SEA) model is derived. The sound field is subdivided into a grazing and non-grazing part where the grazing part refers to waves propagating almost parallel to the suspended ceiling. For estimation of all the inherent parameters in the model, the surface impedance of the suspended ceiling has to be known. A method for estimating the scattering and absorbing effects of furniture and objects is suggested in this paper. The room acoustical parameters reverberation time , speech clarity , and sound strength were calculated with the model and compared with calculations according to the classical diffuse field model. Comparison with measurements were performed for a classroom configuration. With regard to all cases, the new model agrees better with measurements than the classical one.

An Experimental Study of the Performance of a Crossed Rib Diffuser in Room Acoustic Control

This paper presents a crossed rib diffuser (CRD) as an effective tool for room acoustic control. We performed an experimental investigation of its effectiveness using a specimen manufactured for this trial. The CRD is constructed by overlapping two one-dimensional (1D) periodic rib diffusers with different specifications so that they are crossed at non-right angles. The CRD achieves a higher scattering coefficient than 1D periodic rib diffusers in a wide band while maintaining the simple and friendly design of 1D periodic rib diffusers applicable to various architectural spaces. Moreover, inserting an absorbing layer between upper and lower ribs of the CRD, (CRD-A) yields a high broadband absorption coefficient. We first evaluated the random-incidence scattering coefficient of CRD using a 1/5 scaled model in comparison with those of 1D periodic diffusers assessed with a numerical method. Then, absorption coefficients for the CRD and the CRD-A were measured using a reverberation room. Subsequently, an experiment on a small meeting room with a 1D periodic rib diffuser, the CRD and the CRD-A was conducted to present performance of the CRD in room acoustic control. Impulse response measurements and evaluations of reverberation parameters (T20 and EDT) and speech clarity (D50) were conducted. Additionally, we present differences in structure of reflected sounds found for the flat wall, the CRD and the CRD-A visually using a four-channel sound field microphone.

An Archaeoacoustics Analysis of Cistercian Architecture: The Case of the Beaulieu Abbey

The Cistercian order is of acoustic interest because previous research has hypothesized that Cistercian architectural structures were designed for longer reverberation times in order to reinforce Gregorian chants. The presented study focused on an archaeoacacoustics analysis of the Cistercian Beaulieu Abbey (Hampshire, England, UK), using Geometrical Acoustics (GA) to recreate and investigate the acoustical properties of the original structure. To construct an acoustic model of the Abbey, the building’s dimensions and layout were retrieved from published archaeology research and comparison with equivalent structures. Absorption and scattering coefficients were assigned to emulate the original room surface materials’ acoustics properties. CATT-Acoustics was then used to perform the acoustics analysis of the simplified building structure. Shorter reverberation time (RTs) was generally observed at higher frequencies for all the simulated scenarios. Low speech intelligibility index (STI) and speech clarity (C50) values were observed across Abbey’s nave section. Despite limitations given by the impossibility to calibrate the model according to in situ measurements conducted in the original structure, the simulated acoustics performance suggested how the Abbey could have been designed to promote sacral music and chants, rather than preserve high speech intelligibility.