Are classrooms in historical buildings compatible with good acoustics standards?
Abstract and Figures
Many surveys and researches have underlined that the acoustic characteristics of classrooms are strictly connected to performances of students and to the stress of the teachers during lessons. In standard classrooms sound quality can be easily reached without sound amplification but introducing appropriate sound absorbingscattering materials at the ceiling andor at the vertical walls. Nevertheless in historical buildings with vaults or trusses, high walls and many architectural restrictions imposed by district superintendent, it could be very difficult to achieve good acoustics standards with widespread solutions. In this paper the acoustic performances of different classrooms in an historical Monastery actually center of the Faculty of Architecture of the Second University of Naples are analysed. After these analysis, compatible architectural and acoustic solutions to improve the sound quality were developed and tested in laboratory measurements and then applied in some classrooms to verify the benefits.
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... The building materials mentioned in the table refer to the materials related to the acoustic analysis in the relevant research and do not refer to the main building materials. Maffei et al. [47] analyzed the acoustic performance of different classrooms in a historic monastery of the School of Architecture of the Second University of Naples and found that the acoustics were very poor in terms of reverberation and speech intelligibility, mainly due to the large volume and lack of absorbing materials, while the introduction of simple boards built with sustainable materials could achieve good results. Galindo et al. [53] estimated the absorption coefficient of the new building material using an iterative process, conducted acoustic simulation in Mudejar Gothic cathedral, and compared it with the acoustic data measured in the field. ...
... Therefore, for heritage buildings used for modern purposes, acoustic correction using detachable materials and ornaments is a feasible approach. For acoustic correction of heritage building classrooms, the use of new and green materials on the roof of the detachable plate is a feasible approach [47,49]. In addition, methods to satisfy the acoustic transformation without damaging the appearance of heritage buildings are under constant study. ...
As a significant part of heritage building protection, an increasing number of researchers pay attention to the study of the acoustic environment. The purpose of this study was to provide a clear understanding of the status quo of acoustic environment research on heritage buildings and discuss future development directions through a systematic literature review. The PRISMA protocol was used to conduct a systematic evaluation based on 42 studies on the acoustic environment of heritage buildings retrieved from databases such as the Web of Science. Research on the acoustic environment of heritage buildings mainly focused on the following four aspects: the acoustic environment with different functions, the influence of building materials on the acoustic environment, the digitization of acoustic heritage, soundscape measurement, and perception of the historical area. Second, this study discusses the development trend of acoustic environment research of heritage buildings and the shortcomings of current research. Finally, this study provides a comprehensive overview of the acoustic environment research of heritage buildings and offers suggestions for future research.
... and Period of Austro-Hungarian Empire (M=13.42). This result confirms the claims on the acoustics in historic buildings by Maffei, Iannace and Masullo (2008), when they state that historical buildings are poor in regard to acoustics and reverberation. As a reason, they see volume of the rooms and the absence of absorbing materials. ...
The aim of the study was to investigate the students’ perception of the acoustics in terms of academic achievement, high educational buildings from different periods of time, and gender. The quantitative research was conducted among 208 students at higher educational institutions from different historical periods in Bosnia and Herzegovina. The quantitative method was used in order to get desired data. The questionnaire was based on previous studies and examined literature. We found out significant correlation between students’ academic achievement and the acoustics. Besides, the results indicated significant difference between high educational buildings from different periods of time in terms of the acoustics. What’s more, the difference was significant in terms of gender. We believe this study has provided some interesting and valuable information and implications that can be involved in the increasing of students’ performance at the universities in Bosnia and Herzegovina, which will contribute to the improvement in education system of Bosnia in general.
... The need to establish acoustic requirements for higher education environments is confirmed by several studies which testify poor acoustic conditions in more historical University environments 22,23,24,25 . The research highlighted possible future standard parameters for higher education learning environments. ...
The BB93 normative (Building Regulations 93 2015) describes the acoustic requirements to guarantee good speech intelligibility conditions (SI) in schools’ environments, although no specific regulations are given for higher-education learning spaces. In this study, a comparative analysis between subjective and objective data collected in two classrooms and three lecture theatres at Solent University was carried out; the research was
aimed to explore any further constraint which might be relevant within a higher-education environment. The data collected confirms the relationship between background noise levels and perceived noise annoyance and opens suggestions for more restrictive background noise requirements. The investigation also shows that both upper and lower boundaries of reverberation time (RT), as a function of classroom’s volume, should be recommended to compensate for the vocal fatigue reported by members of staff. Furthermore, the authors
suggest that Clarity (C50) and Strength (G) should be included within an updated regulation standard. Indeed, a comparison between quantitative and qualitative data demonstrates how these additional acoustical parameters might better define the acoustic properties of classrooms than RT values alone. Lastly, advantages of employing the STI for PA systems to assess the effectiveness of any voice reinforcement systems present in university learning spaces will be discussed.
... In order to comply with this set of restrictions a generally accepted solution is the use of tapestries and paintings which, being simply hung to the walls, provide the highest respect of the underlying surfaces. Such solutions are suggested particularly for churches [1] but have been tested also in other historical buildings used as schools[2]. The acoustic behavior of such treatments has been studied with particular reference to simple woven fabrics where the effect of fabric composition and air space was investigated [3]. ...
Churches and other buildings listed as cultural heritages often require acoustical treatments in
order to control reverberation time and other acoustical parameters. However, due to their high
artistic value the use of conventional sound absorbing materials is generally forbidden or, at least,
highly discouraged. Conversely, the use of paintings and tapestries is often more tolerated even
though their acoustic effect needs to be carefully evaluated as it largely depends on the type of
painted surface (wood, canvas) as well as on the type of painting. The results of the on-site and
laboratory measurements of absorption coefficients of different types of paintings and tapestries
are discussed. Finally, in order to obtain improved absorbing characteristics, the combined effect
of painted canvases covering porous materials is investigated. Results show that, in agreement
with theoretical models, impermeable treatments (resulting from the use of acrylic or oil colours)
mostly affect high frequency absorption
... Often the classrooms are located in historical buildings, where for aesthetic and historical reasons it is difficult to install sound-absorbing panels for acoustic corrections; the classrooms are not regular in shape and the ceilings are not level [1], [2]. To improve the acoustic characteristics of the classrooms, sound-absorbing materials must be installed in an appropriate manner, but with non fixed structures, as they are historical buildings. ...
... The dimensions of the panels are 1,40 m x 0,60 m, thickness 50 mm. The coating with the juta was chosen because of its characteristics of low resistivity (large woof) which do not affect the sound absorbing properties of the "kenaf" [4]. The pupils selected cartoon images to decorate the panels and they helped during the drawing and system build-up phases (Fig.4). ...
Worldwide research has demonstrated the influence of bad acoustic conditions inside primary schools on pupils' learning and achievements and on teachers' stress. It has been also demonstrated that noise levels during school activities can be over 75 dB(A). Although the lack of sound insulation and sound absorbing units is of main concern for the phenomena, social and environmental context of the school can have also a dominant effect. In this paper are presented the results of a pilot study named "Sshh…school" conducted in two schools located in different places (a strongly urbanized area and a small village). The pilot study had the aim to sensitize all school actors (management, teachers, parents, pupils) to the problem and to find together the possible remedies to control it. Among others the effects of an information and instruction campaign and the introduction of friendly shared and sustainable absorbing materials were investigated.
... Ulteriori due allestimenti basati su soluzioni progettuali di miglioramento della qualità acustica sono stati implementati nel modello: il primo basato sull'utilizzo di un controsoffitto fonoassorbente commerciale adatto per impieghi nelle aule scolastiche, il secondo sull'adozione di pannelli fonoassorbenti sostitutivi dei più classici poster o cartine geografiche . I pannelli fonoassorbenti introdotti sono costituiti in fibre naturali di kenaf e fibre di sostegno in poliestere con densità di 100 kg/m 3 e spessore di 60 mm [7]. Figura 1 – Modelli di realtà virtuale degli scenari proposti A ciascun materiale presente nel modello, realizzato con il software ODEON, sono stati associati i rispettivi coefficienti di assorbimento in bande di ottava utilizzando la banca dati dello stesso software. ...
In the current regulations, acoustic requirements to guarantee good speech intelligibility (SI) conditions in primary schools' environments are published within the BB93 normative (Building Regulations 93 2015) but no specific recommendations or values are given for higher educational learning spaces. |n addition, because Universities vary from usual primary or secondary schools' environments, they present additional and different constraints. In this thesis, the acoustic performance of five teaching spaces of Solent University was analysed and compared with subjective responses of students and staff members in order to point out the main constraints which might be found within a University environment. A relationship was found between background noise levels, which were higher than the standard requirements, and the perceived annoyance reported by staff members, suggesting a target for more restrictive background noise requirements, especially for higher room volumes. Conversely, although the Reverberation Time (RT) measurements of the five spaces were conform to English requirements specified in the BB93 document, vocal fatigue issues were reported by staff members, suggesting the need for lower and upper RT values as a function of classrooms volumes, as suggested, for example, in the DIN18401 German legislation. After analysing both quantitative and qualitative data, this study suggests that the values of Clarity (C50) and Strength (G) should also be included within an updated regulation standard, in order to both better represent auditory perception and to assess appropriate speech clarity and loudness levels among several distances within large lecture theatres. Lastly, given the relevance of sound reinforcement systems to improve SI while assuring vocal comfort for the lecturers, the Speech transmission index for PA systems (Sti-Pa) method should be used to assess the effectiveness of classrooms installed sound reinforcement systems.
The acoustic correction inside classrooms located in historical buildings using absorbent panels is difficult for aesthetic reasons. Furthermore, architectural restrictions are often imposed to preserve the historical heritage. The acoustic measurements inside the classrooms show high reverberation time values, which imply an adverse environment for speech reception. In this paper the reverberation time in classrooms located in historical buildings was reduced by installing removable sound absorbent panels. The panels were made with “green material”. The absorbent material was obtained by crushing giant reeds of sweet water, a plant which grows quickly in wetlands. The crushed material was then put in jute sachets, installed in the wooden frames and covered with different colours jute cloth for aesthetics. Acoustic measurements were made in the classrooms with smooth plaster walls, without students. A virtual model of the classroom was drawn with 3D CAD. The surface area covered with green material absorbent panels was evaluated by the software Odeon. After the installation of the absorbent panels, comparisons between the virtual classroom acoustic properties and the real classroom acoustic properties were made to validate the effect of the green absorption panels.
Ce), luigi.maffei@unina2.it 1. Premesse e considerazioni generali Gli ambienti scolastici sono sistemi complessi. Essi devono assolvere diverse fun-zioni: insegnamento con trasmissione vocale, studio individuale, attività didattiche spor-tive e musicali, attività ricreative. Tutte funzioni che necessitano diversi livelli di con-centrazione e coinvolgimento di studenti e docenti. Le condizioni acustiche negli ambienti scolastici sono anche esse complesse. Aule, palestre, piscine, possono essere esposte a sorgenti sonore esterne all'edificio (traffico stradale, ferroviario, aereo, impianti) ma anche a sorgenti sonore interne quali attività che si svolgono nelle aule limitrofe o nei corridori, impianti di condizionamento, appa-recchiature per le attività didattiche (stampanti, computers). E' nondimeno di estrema importanza il rumore generato dagli stessi allievi durante le attività scolastiche quotidiane. In letteratura sono stati pubblicati diversi studi su questo aspetto [1,2]. I valori del livello della pressione sonora all'interno delle aule scolastiche dipendono dal rumore di fondo, dalla configurazione dell'aula, dalla presenza o meno di materiale fonoassorbente, dal grado di occupazione, dall'età degli allievi, dal tipo di at-tività ma anche, e non meno importanti, da aspetti sociali e pedagogici. Numerose e approfondite ricerche a livello internazionale confermano come la scar-sa qualità dell'acustica delle aule per la didattica possa generare effetti negativi sul pro-cesso di apprendimento degli alunni [3] con conseguente calo delle prestazioni, ma an-che eccessivi sforzi vocali degli insegnanti con conseguenti patologie nonchè innesco di stress per insegnanti e allievi [4]. Non trascurabile è anche l'aspetto del rischio da rumore in ambienti particolari come palestre e aule di conservatori per gli insegnati di educazione fisica [5] e di musica rispettivamente [6]. Esistono peraltro numerosi studi incentrati sulle migliori tecniche da applicare per il controllo delle condizioni acustiche negli edifici scolastici. Inserimento di materiale fo-noassorbente nelle aule, pareti esterne e divisori interni con proprietà fono isolanti, ma anche studio di opportuni lay-out, inserimento di arredi con funzioni anche fonoassor-benti, sono soluzioni non complesse e di sicuro effetto. Accanto ad interventi tecnici, possono essere previsti anche interventi organizzativi e/o gestionali: formazione agli
In this paper the physical and acoustical investigation on a newly developed sound absorbing porous plaster is reported. The plaster contains volcanic pearlite added with nanoparticles of precipitated calcium carbonate, in order to obtain high porosity and good mechanical properties.
The acoustical optimization of such plasters has been carried out on samples having small dimensions by measuring physical properties (airflow resistivity, porosity and tortuosity) and acoustical quantities at normal incidence (complex and surface acoustical parameters).
Furthermore, results related to the reduction of the reverberation time, due to the acoustical treatment of some walls in a closed spaced, will be presented.
Detailed acoustical measurements were made in 41 working elementary school classrooms near Ottawa, Canada to obtain more representative and more accurate indications of the acoustical quality of conditions for speech communication during actual teaching activities. This paper describes the room acoustics characteristics and noise environment of 27 traditional rectangular classrooms from the 41 measured rooms. The purpose of the work was to better understand how to improve speech communication between teachers and students. The study found, that on average, the students experienced: teacher speech levels of 60.4 dB A, noise levels of 49.1 dB A, and a mean speech-to-noise ratio of 11 dB A during teaching activities. The mean reverberation time in the occupied classrooms was 0.41 s, which was 10% less than in the unoccupied rooms. The reverberation time measurements were used to determine the average absorption added by each student. Detailed analyses of early and late-arriving speech sounds showed these sound levels could be predicted quite accurately and suggest improved approaches to room acoustics design.
The aim of the present experiment was to examine teachers' attention, episodic and semantic memory during road-traffic noise (66 dBA Leq) exposure. Sixty-four male and female teachers in the age of 35-45 and 55-65 years were recruited from local upper level regular schools and randomly assigned to a road-traffic noise group or a silent control group. Self-reports of affect were taken and objective hearing tests. It was predicted that road-traffic noise would impair attention, recall and recognition in episodic memory. No decrements in retrieval from semantic memory were expected. The results showed that road-traffic noise impaired recall, but not recognition in episodic memory. Contrary to expectation road-traffic noise also impaired retrieval from semantic memory. However, no impairment in attention was found, and attention was therefore ruled out as a mediator of the decrements in memory. Neither, objective hearing status or self-reported affect mediated the road-traffic effects on memory. Nor were there any interactions between noise and age.
A technique is presented for evaluating the normal acoustic impedance at the surface of a panel of absorbing material in a free field. The evaluation is achieved by measuring the pressure and the acoustic velocity with two microphones set very close to the panel. This technique allows measurements of impedance for panels of area about 1 m2, the two microphones being located very close to the panel so that, contrary to other methods, the effect of the finite dimension of the panel is negligible. Because of the very small spacing between both microphones, this technique allows precise measurements only for frequencies higher than 500 Hz.
A child’s ability to hear and communicate with speech in the classroom is influenced by several factors, including talker characteristics (level, clarity, dialect), the acoustical environment (noise level, reverberance), and listener characteristics(hearing status, cognitive development, language level, exposure to English). This presentation will review and assess the relative contribution of each factor to the communication requirements of the classroom. An emphasis will be placed on the large individual differences in listener characteristics that are likely to exist in contemporary classrooms, and their impact on the requirements of the acoustic environment for effective speech communication. Recent findings from this laboratory and from other researchers that document the range of speech communication abilities in both difficult and easy listening conditions among school‐age children will be reviewed. Finally, an initial proposal for acceptable levels of background noise and reverberance in classrooms based on these findings will be offered. The rationale for this proposal is that noise and reverberance levels must be low enough to allow children with a wide range of listener characteristics to communicate with speech easily and effectively in the classroom. [See NOISE‐CON Proceedings for full paper.]
Human learning depends strongly on verbal learning. Research has shown that the quality of the acoustical environment is a significant element that influences verbal learning. Noise and room acoustical peculiarities are the main descriptors of acoustical comfort pertaining to learning spaces. The adverse effects of inappropriate acoustical environments on the learning-teaching activities in educational buildings have been summarized by an abundance of research and other published data. Recommendations for both interior noise levels and equipment noise in school classrooms have been documented in a variety of national and international noise policies, guidelines, standards, and regulations. However the importance given to the subject, the content and the context of the requirements depends basically on the general noise policies of the countries involved. This article presents and compares, to a reasonable extent, the acoustical requirements for educational buildings of some European countries. National guidelines, recommendations, regulations and standards are the basic documents referred to in this study.
The acoustical characteristics of 14 university classrooms at the University of British Columbia were measured before and after renovation—seven of these are discussed in detail here. From these measurements, and theoretical considerations, values of quantities used to assess each classroom configuration were predicted, and used to evaluate renovation quality. Information on each renovation was determined with the help of the university campus-planning office and/or the project acoustical consultant. These were related to the evaluation results in order to determine the relationship between design and acoustical quality. The criteria focused on the quality of verbal communication in the classrooms. Room-average Speech Intelligibility (SI) and its physical correlate, Speech Transmission Index (STI), were used to quantify verbal-communication quality. A simplified STI-calculation procedure was applied. The results indicate that some renovations were beneficial, others were not. Verbal-communication quality varied from ‘poor’ to ‘good’. The effect of a renovation depends on a complex interplay between changes in the reverberation and changes in the signal-to-noise level difference, as affected by sound absorption and the source outputs. Renovations which reduce noise are beneficial unless signal-to-noise level differences remain optimal. Renovations often put too much emphasis on adding sound absorption to control reverberation, at the expense of lower speech levels, particularly at the backs of classrooms. The absorption and noise contributed by room occupants has apparently often been neglected.
This paper describes the results of a large-scale questionnaire survey that ascertained children's perceptions of their noise environment and the relationships of the children's perceptions to objective measures of noise. Precision, specificity, and consistency of responding was established through the use of convergent measures. Two thousand and thirty-six children completed a questionnaire designed to tap (a) their ability to discriminate different classroom listening conditions; (b) the noise sources heard at home and at school; and (c) their annoyance by these noise sources. Teachers completed a questionnaire about the classroom noise sources. Children were able to discriminate between situations with varying amounts and types of noise. A hierarchy of annoying sound sources for the children was established. External L(Amax) levels were a significant factor in reported annoyance, whereas external L(A90) and L(A99) levels were a significant factor in determining whether or not children hear sound sources. Objective noise measures (L(A90) and L(A99)) accounted for 45% of the variance in children's reporting of sounds in their school environment. The current study demonstrates that children can be sensitive judges of their noise environments and that the impact of different aspects of noise needs to be considered. Future work will need to specify the factors underlying the developmental changes and the physical and location dimensions that determine the school effects.
A questionnaire is developed to evaluate perception of the listening environment by university students. The objectives were to develop a questionnaire-based measurement tool, derive a measure of perceived classroom-listening quality, use the questionnaire to investigate factors that enhance, impair, or do not affect perceived listening quality, and consider the implications for classroom design. The questionnaire was administered to over 5700 students in 30 classrooms at one university. Physical and acoustical measurements were also performed in each classroom. The questionnaire included items that recorded aspects of student perception, as well as individual, course-, and instructor-specific factors. Responses to 19 perception items generated a perception of listening ease (PLE) score for each student and a classroom-average score. Decreased PLE was associated with women, English-second-larguage students, those with hearing impairment, students not interested in the course material, and those who found the material difficult. Increased PLE was associated with higher speech transmission index, acceptable lighting, temperature and seating, better instructor voice, increased visual-aid use, and easier course material. Results indicate that PLE is a useful measure of student perception of the classroom-listening environment, and that optimal classroom acoustical design must take into consideration "in-use" conditions, as well as classroom physical characteristics.