Trajectories in classroom acoustics: The vocal behaviour of teachers

Classroom acoustics was one of the main research themes of Murray Hodgson, which I had the chance to know in Rome, at the ICA Conference in 2001, when I was at the beginning of my working path, and to further have as scientific converser in many other occasions. In Ferrara, in 2003, he concluded his presentation of a course on classroom acoustics with the hint that the teachers’ voice problems should have been object of future studies. I have been working on this matter for seven years and this work summarises the results and the perspectives related to the assessment of teachers’ vocal behaviour. In particular, teachers' voice monitoring during daily working activities has been recently based on wearable vocal analysers equipped with contact sensors, which allow for measuring parameters related to vocal effort, vocal loading and also to voice quality. Results obtained during experimental campaigns that took place in the last years, from kindergarten to university, and that involved healthy and unhealthy teachers, are presented in this work. The relationships with classroom acoustics, both in terms of noise and too low or excessive reverberations, and the subjective outcomes of the teachers, are also discussed

Effect of vegetation on sound fields in idealised urban open spaces

Noise pollution is a major environmental problem within the EU and during the last years vegetation was examined for its benefits in increasing health and well-being of citizens from different viewpoints, including noise control and soundscape enhancement. This work focuses on numerical simulations to investigate the effectiveness of vegetation for controlling sound fields, especially in terms of the abatement of traffic noise. Two idealised urban squares were studied, one rectangular and one octagonal. Three plant types, climbing plants (ivy), living green walls with soil substrate and plants in pots (nephrolepis exaltata), were used in this investigation, based on their measured properties in laboratory, and four aspects of the use of vegetation were evaluated: effect of the amount of vegetation, effect of changing in the scattering coefficient of vegetation, effect of vegetation in different receiver positions and effect of vegetation on different groups of receivers. Parametric studies on the determination of a line source and on the definition of sound power levels referred to traffic noise were also developed. Three simulation tools were used, namely CATT-Acoustic®, CRR (Combined Ray-tracing and Radiosity) and Odeon

Applicability of multi-objective optimization in classroom acoustics design using analytical and geometrical acoustic models

The purpose of this study is to improve the acoustic quality of classrooms for a better teaching-learning process by the development of a routine which aids in the optimization of typology, extension and position of acoustic materials. It is a tool addressed to architects, building designers and professionals alike that are involved in the planning, construction and renovation of rooms. One classroom in Turin has been selected for this study and a basic geometric model has been built in Grasshopper, that serves as the environment for parametric investigation and improvement of acoustics parameters. Reverberation time and STI, which are considered as the most important descriptors in classroom acoustics have been determined using theoretical calculations (Sabine, Eyring and Barron&Lee theories) and geometrical acoustic (GA) simulations (Pachyderm). The latter allows to take into account the scattering properties of surfaces and different combinations of all the acoustic materials Finally, Octopus has been used to perform multi‐objective optimization runs considering as objectives the acoustic parameters and the acoustic design/renovation costs. The algorithm has been developed in order to allow to choose different optimization sets depending on the material or the type of acoustic treatment to optimize. Said model provides, essential information on the acoustic quality of the classroom and recommendations on how to increase it by improving teaching-learning activities; which would normally be time-consuming. The results show that the GA simulations and theoretical calculations are compatible for the solutions without scattering properties. However, it needs further development in order to extend its application field in fact right now operating on the Grasshopper canvas would require significant knowledge on the designer?s behalf concerning parametric design and acoustics

Alternative Spaces for Learning: Reversible Acoustic Treatments for Transformation of Spaces into Classrooms During COVID Era

The design of acoustic comfort in classrooms is a challenging issue. It became a crucial aspect during the Covid-19 pandemic regarding class life organization, as for the latter large spaces for teaching were required in order to guarantee the minimum distance between the occupants to limit the spread of Covid-19, and it was important to ensure their acoustics functionality for the performance of lessons. To this aim, this investigation is to provide a guide (for school principals, administrators, safety managers, architects and engineers, acousticians) where easily implementable solutions for different types of school buildings are detailed in various case studies and they are an example in case of environments similar in shape and volume. In particular the focus is put on the transformation of school spaces created for different purposes than normal classrooms (e.g., corridors, atria, sports halls) into classrooms for teaching. Different layouts of the furniture and sound-absorbing materials have been applied and analysed by simulations (Odeon 15) comparing the results with the standardized optimal values and with those of the actual environments obtained through an extensive measurement campaign. Eight schools were taken into account as case studies, representing the Italian school heritage and including elementary schools, middle schools and high schools. A total of 26 different spaces with a volume varying in the range 135-2800 m3 were analysed. For each of them, both general analyses at the overall environment level and more specific ones for single receivers located over the area occupied by the students were carried out. As a result, it should be highlighted that the proposed solutions could not be fully acoustically optimized for all of the spaces, as the analyses also took into consideration an affordable cost, the speed of realization and the reversibility of the intervention

Listeners Sensitivity to Different Locations of Diffusive Surfaces in Performance Spaces: The Case of a Shoebox Concert Hall

Diffusive surfaces are considered as one of the most challenging aspects to deal with in the acoustic design of concert halls. However, the acoustic effects that these surface locations have on the objective acoustic parameters and on sound perception have not yet been fully understood. Therefore, the effects of these surfaces on the acoustic design parameters have been investigated in a real shoebox concert hall with variable acoustics (Espace de Projection, IRCAM, Paris, France). Acoustic measurements have been carried out in six hall configurations by varying the location of the diffusive surfaces over the front, mid, and rear part of the lateral walls, while the other surfaces have been maintained absorptive or reflective. Moreover, two reference conditions, that is, fully absorptive and reflective boundaries of the hall have been tested. Measurements have been carried out at different positions in the hall, using an artificial head and an array of omnidirectional microphones. Conventional ISO 3382 objective acoustic parameters have been evaluated in all conditions. The results showed that the values of these parameters do not vary significantly with the diffusive surface location. Moreover, a subjective investigation performed by using the ABX method with auralizations at two listening positions revealed that listeners are not sensitive to the diffusive surface location variations even when front-rear asymmetric conditions are compared. However, some of them reported perceived differences relying on reverberance, coloration, and spaciousness

THE EFFECT OF CLASSROOM ACOUSTICS ON STUDENTS’ LEARNING PROCESSES: SELECTION OF OBJECTIVE PARAMETERS AND PROVISION OF A MEASUREMENT PROTOCOL

Since the students’ learning process is affected by classroom acoustics, this work is based on a literature review aiming at identifying the acoustical parameters that have major influence on students’ academic performances. The review strategy involved three different approaches and resulted in more than 30 selected papers, of which only a few provided information on the effects of the acoustics of the environment on learning. The indexes that turned out to have the greater influence on students' performance were therefore considered on the evaluation of acoustical quality in elementary school classrooms through in-field measurements. Room acoustics and intelligibility indices in both occupied and unoccupied conditions of twenty-nine first-grade classrooms belonging to 13 school buildings in Turin that differ in location and typology, were gathered in the study. Then, the association between objective parameters was assessed with linear regression analysis and results of previous studies were confirmed. In addition to that, new important considerations useful for the creation of a simplified protocol that can be universally applied when performing acoustic measurements in classrooms emerged, so that comparisons across several environments can be performed

Improved Room Acoustics Quality in Meeting Rooms: Investigation on the Optimal Configurations of Sound-Absorptive and Sound-Diffusive Panels

This work deals with the improvement of the room acoustic quality of two medium sized meeting rooms through the investigation of the optimal placement of absorption and diffusive panels on the walls and ceiling. Acoustic measurements have been carried out in the existing untreated rooms with ODEON 13 room acoustics measurement and prediction software, and the Adobe Audition plugins Aurora. Simulations of different combinations of sound absorption and diffusion treatments have been carried out with the updated version of the software, ODEON 15. The panels were positioned in the meeting rooms following the guidelines of the DIN 18041 standard and the scientific literature. The results advise the application of absorptive materials on the ceiling or around the borders, creating a reflective middle area, and on the upper part of one the lateral walls, including the rear wall. Configurations with diffusers do not generally bring significant improvements. The Speech Transmission Index (STI) is a less sensitive parameter for the different acoustic scenarios, compared to Reverberation Time (T) and Clarity (C50). The research also outlined a design workflow, useful to successfully design meeting rooms and rooms for speech in general, which allows to determine the optimal number and location of acoustic panels and to minimize the costs

Influence of classroom acoustics on the vocal behavior of teacers

Erroneous vocal behavior of teachers and their changes in the voice production due to poor acoustics in classrooms can be investigated through recently developed voice-monitoring devices. These devices are portable analyzers that use a miniature contact-microphone glued to the jugular notch in order to sense the skin acceleration level due to the vibration of the vocal folds. They estimate the Sound Pressure Level (SPL) at a certain distance from the speaker's mouth provided that a preliminary calibration procedure is performed, the fundamental frequency and the time dose. Two different devices are compared in this work: the former is a commercial device, whose phonation sensor is a small accelerometer; the latter, recently developed by the authors, uses an electret condenser microphone to sense the skin acceleration level. SPL and fundamental frequency are estimated over fixed-length frames and the results that refer to a sample of 25 primary school teachers and a university professor are analyzed. The duration of the voice and pause periods is investigated in order to detect the peaks of occurrence and accumulation in different conditions of reverberation. A method for the detection and analysis of the emphatic speech is also propose

The effect of walking sounds from different walked-on materials on the soundscape of urban parks

Urban parks are essential environmental resources in contemporary cities, for the substantial social and psychological relief they provide for local communities. In recent years, the potential of the soundscape approach for enhancing the ecological contribution of such environmental assets has been intensely investigated. Although, researchers tended to focus on the perception of people “staying” in the park, whilst it is important to consider how the sonic environment would be dynamically perceived by users walking across the park. Within this framework, the present study aimed to investigate the effect of different footpath materials on soundscape quality and walking quality perception for people walking in an urban park, considering that the experience of such users is affected by both the background acoustic environment of the park and their walking sound. To this purpose, a laboratory experiment was carried out with 25 participants. Four different walked-on materials that are likely to be used in urban parks were tested: grass, wood, stone and gravel. Results show that the material factor has a significant effect on both auditory and haptic perception. Furthermore, positive correlations can be observed between auditory and haptic variables, confirming that the soundscape appreciation for people walking in urban parks is likely to be affected also by other but aural sensory modalities. The paper ultimately points out that it is possible to re-think the approach to urban parks design and more specifically to the footpaths and the walking sounds that their materials are likely to produce

Between the archaeological site and the contemporary stage: an example of acoustic and lighting retrofit with multifunctional purpose in the ancient theatre of Syracuse

A research conducted on the contemporary use of ancient theatres is presented, focusing on sustainable solutions for passive acoustics and artificial lighting devices. The case study is the theatre of Syracuse, well known as archaeological tourist attraction and as traditional stage for theatrical events. A retrofit was suggested to avoid the use of loudspeakers in the theatre during representations, through the selection of the best performing orchestra shells. For the lighting part, the study focused on the theatre as archaeological site, improving the monumental light system present in the theatre from the maintenance and energy saving points of view