ArticlePDF Available

Guidelines on acoustic treatments for school buildings proposed by the Architectural Institute of Japan

Authors:

Abstract and Figures

In order to realize effective educational activities in school buildings, acoustic conditions for verbal communication and calm atmosphere are essentially important. The Architectural Institute of Japan set up a working group to investigate acoustical criteria for schoolrooms and to publish a new guideline to improve the acoustic conditions in school buildings. In this paper, the activities being made in the working group and the outline of the new criteria are introduced.
Content may be subject to copyright.
Guidelines on acoustic treatments for school buildings
proposed by the Architectural Institute of Japan
Toshiko Fukuchi* and Kanako Ueno**
* Nagata Acoustics Inc.
t.fukuchi@nagata.co.jp
** Institute of Industrial Science, University of Tokyo
ueno@iis.u-tokyo.ac.jp
Abstract
In order to realize effective educational activities in
school buildings, acoustic conditions for verbal
communication and calm atmosphere are essentially
important. The Architectural Institute of Japan set up a
working group to investigate acoustical criteria for
schoolrooms and to publish a new guideline to improve
the acoustic conditions in school buildings. In this paper,
the activities being made in the working group and the
outline of the new criteria are introduced.
1. Introduction
In Japan, the side-corridor type” arrangement of
schoolrooms is most popular as the stereotype design
for a long time. Since the 1970s, however, educational
policy has gradually changed and new architectural
ideas to realize the new educational policies are being
adopted. As an example, open-type classroom, which
is clearly disadvantageous from acoustical viewpoint, is
becoming popular for elementary schools [1]. Besides,
the way of school building design is now diversifying
and various acoustic problems such that the spaces with
different functions are connected and large rooms have
excessive reverberation are often seen.
At present, the Architectural Institute of Japan (AIJ)
shows the guideline for acoustical properties of
schoolrooms regarding sound insulation and ambient
noise level [2]. However, the importance of acoustical
quality in school buildings has not been fully
recognized in architectural design. Besides, there is a
movement in the AIJ to reconsider the existing
guidelines of various building performance to suit the
recent situation.
From these background conditions, a working group
for the preparation of new acoustical guidelines for
school buildings has been set up in the AIJ in April
2003 and the new criteria are being discussed. In this
paper, these activities and present draft of the guidelines
are introduced.
2. Scheme of the guidelines
The work to draft the new acoustic guidelines is being
made by referring the existing criteria [2] and those in
foreign countries [3]. The main points are ambient noise
level in schoolrooms, sound insulation between rooms
and reverberation in rooms. The draft of the
requirements for these points is as follows. The values
set for each requirement are recommendations as the
desirable acoustic conditions for school. They will be
discussed furthermore as the acoustic guideline for
construction and renovation of school buildings and the
final version will be published in March 2005 as an AIJ
Environmental Standard.
2.1. Ambient noise level in schoolrooms
By considering the condition that the school activities
are not disturbed, the criteria of the ambient noise level
in classrooms are set as shown in Table 1. The criterion
value depends on the type and purpose of the rooms.
The noise levels shown in the table are the values
measured under the condition that the room is
unoccupied, the doors/windows are closed and HVAC
system is working. According to these criteria, the sound
insulation of building facade has to be designed properly
by considering the environmental noise condition and
noises generated by such building equipment as HVAC
system have to be controlled.
Table 1: Criteria for ambient noise level in classrooms
Room type LAeq
R1: Rooms where quiet condition is
especially required (music room,
auditorium, school infirmary)
35
R2: Rooms where the quiet condition is
desirable (classroom, teachers room) 40
R3: Rooms for active works (craftwork
room, gymnasium) 45
2.2. Sound insulation
In order to prevent the acoustic interference between
spaces during school activities, partition walls should
have sufficient sound insulation properties both for air-
borne sound and floor impact sound. By considering
these points, the criteria for sound insulation are
tentatively decided as shown in Table 2 for air-borne
sound insulation and in Table 3 for floor impact sound
insulation. They are given by considering the required
Tu2.B1.1 II - 909
ambient noise level and supposed noise level generated
in each type of the rooms.
Regarding the air-borne sound insulation, the criteria
are shown in two kinds of indices: one is the arithmetic
mean value of the sound pressure level difference in
octave bands from 125 Hz to 2k Hz, and the other is D-
value (in parentheses) which has been uniquely used in
Japan for a long time [4].
Regarding the floor impact sound insulation, the
criteria are also shown in two kinds of indices: one is A-
weighted sound pressure level LA and the other is L-
value (in parentheses) which has been used in Japan [5].
For the measurement of these indices, the standard light
impact source (tapping machine) and the standard heavy
impact source (tire) specified in JIS A 1418-1 and -2 are
used and LAeq and Fast-maximum value of LA are
measured for the tapping machine method and the tire
method, respectively.
Table 2: Criteria for air-borne sound insulation
Room type Receiving room
Source room R1*1 R2*1
Ambient noise limits
Room type
LAeq*2
35[dB]
40[dB]
Rooms mainly for
speech communication
(classroom etc.)
80
[dB]
45
(D-45)
40
(D-40)
Rooms for active works
(gymnasium, music
room, auditorium, etc.)
95
[dB]
60
(D-60)
55
(D-55)
*1: Room types defined in Table 1
*2: Supposed level generated in the source room
Table 3: Criteria for floor-impact sound insulation
Room type Receiving room
Source room R1*1 R2*1
Ambient noise limits
Room type 35[dB]
40[dB]
Rooms where speech
communication is mainly
conducted (classroom etc.)
50
(L-50) 55
(L-55)
Rooms where the higher impact
sound is generated (gymnasium,
etc.)
40
(L-40) 45
(L-45)
*1: Room types defined in Table 1
2.3. Reverberation in schoolrooms
To realize high speech intelligibility and sound
insulation, excess reverberation must be prevented for
various kinds of spaces in school buildings. For this aim,
the desirable sound absorption treatment is specified in
reverberation time RT and in average sound absorption
coefficient α as shown in Table 3. These values are for
the mean values in 2-octave bands including 500 Hz and
1k Hz frequency bands under furnished and unoccupied
condition. For such special rooms as music rooms, the
frequency characteristic of reverberation time should be
carefully considered. In addition, it is recommended that
the reverberation in such spaces in school buildings as
corridors and entrance halls should be carefully
controlled to realize quiet acoustic environment.
Table 4: Recommended reverberation time
Room type RT α
Classrooms (V
200) 0.6 0.2
Classrooms (V
300) 0.7 0.2
Rooms where shorter reverberation is
suitable (audio visual rooms, etc.) 0.4 0.3
Rooms where longer reverberation is
suitable (music practice rooms, etc.) 0.8 0.15
Large spaces (gymnasiums, etc.,
V
5000) 1.5 0.2
3. Further works
In order to realize the acoustically well treated school
buildings, it is very important not only to show the
recommendation value but also to make architects
understand the necessity of the acoustic treatment and
the ways to realize the performances. It should be also
noted that the criteria will be only for the most ordinal
buildings whereas acoustic treatment is even more
important for such cases as open-type classrooms,
combined facilities, classrooms for hearing impaired
children, room with high-quality electro-acoustic
equipment, and so on. To instruct the solution in these
cases, a guidebook for architectural design is also
preparing, in which practical examples of acoustic
treatment for school rooms, information of acoustic
environment in school buildings, results of the
questionnaire surveys for teachers and children and
typical acoustical problems in schools will be included.
4. References
[1] H. Tachibana and K. Ueno, Study on acoustical
conditions in elementary schools of open-plan type
in Japan, Internoise 2002, N323, 324.
[2] Edited by Architectural Institute of Japan, Standard
of sound insulation performance and planning
guide for architecture (second edition), 1997.
[3] Z. Karabiber and M. Vallet, "Classroom acoustics
policies An overview", Euronoise Naples 2003
Paper ID: 048-OL, 2003.
[4] JIS A 1419-1, Rating of sound insulation in
buildings and of building elements Part 1:
Airborne sound insulation, 2000.
[5] JIS A 1419-2, Rating of sound insulation in
buildings and of building elements Part 2: Floor
impact sound insulation, 2000.
II - 910
... Several acoustical standards (national or international) provide reference values for RT that should be observed when a certain room is built for a certain purpose. In the case of classrooms, specific standards can be cited, from countries such as Germany, Japan, United Kingdom, and USA [34,35,43,44]. In Brazil, the standard that specifies RTs for closed spaces (furnished and unoccupied) is the NBR 12179 [33]. ...
... Although it does not specifically mention classrooms, it shows a curve for optimum RT in the frequency of 500 Hz for a conference room, which will be applied here for classrooms. In Japan [43], RT values are for the mean in 2-octave bands including 500 Hz and 1000 Hz, and RT is measured with furnished but empty classrooms. In the United Kingdom the Build- ing Bulletin BB-93 [44] indicates that RT is given in terms of the maximum mid frequency reverberation time T mf , the average RT in the 500 Hz, 1000 Hz and 2000 Hz octave bands, and RT should be measured with the classroom empty and unfurnished. ...
Article
The acoustic quality of a standard classroom in a public school was evaluated based on measurements of the reverberation time and ambient noise level inside and outside classrooms. The reverberation time was measured in three conditions: a) unoccupied classroom, b) classroom occupied to 50% of its capacity, and c) classroom occupied 100%. Concomitantly to the assessment of the acoustic quality of classrooms, teachers and students' perception of noise inside and outside the school was also investigated. Teachers and students stated that they perceive the presence of noise in their daily school activities and that it is bothersome to a greater or lesser degree. Among their main reactions to noise, the teachers pointed out: 1) the need to speak more loudly, 2) loss of concentration, 3) irritability, restlessness and edginess, and 3) headaches, fatigue and buzzing in the ears. The main reactions among the students were: 1) difficulty to concentrate, 2) headache, 3) the need to speak more loudly, 4) edginess, 5) buzzing in the ears, 6) irritability and restlessness, and 7) fatigue.
... (1) The acoustic parameters used for classroom acoustic environment control. To achieve a good classroom acoustic environment, some countries have promulgated corresponding standards and recommendations, mainly for the control of RT and background noise level (BNL) (WHO 1999;BB93 2003;Fukuchi and Ueno 2004;ANSI/ ASA 2010;AS/NZS 2016;DIN 2016). However, these standards are not uniform in terms of the recommended RT and BNL values, and the ranges for them are relatively large. ...
Article
The acoustic environment of the classroom is one of the most important factors influencing the teaching and learning effects of the teacher and students. It is critical to ensure good speech intelligibility in classrooms. However, due to some factors, it may not be easy to achieve an ideal classroom acoustic environment, especially in large-scale multimedia classrooms. In a real renovation project of 39 multimedia classrooms in a university, seven typical rooms were selected, and the acoustic environment optimisation design and verification for these multimedia classrooms were performed based on simulation. First, the acoustic and sound reinforcement design schemes were determined based on the room acoustics software ODEON. Next, the effects of the optimisation design were analysed, and the simulated and measured results were compared; the accuracy of using the reduced sound absorption coefficients, which were determined empirically, was also examined. Finally, the recommended reverberation times (RTs) in multimedia classrooms corresponding to speech intelligibility were discussed, the effectiveness of the speech transmission index (STI) as a primary parameter for classroom acoustic environment control was considered, and the acoustic environment under the unoccupied and occupied statuses was compared. The results revealed that although there are many factors influencing the effect of classroom acoustic environment control, an adequate result can be expected on applying the appropriate method. Considering both the acoustic design and visual requirements also makes the classroom likely to have a good visual effect in addition to having a good listening environment.
... In Japan, RT values represent the average in 2-octave bands including 500 Hz and 1000 Hz, and RT is measured in the furnished and unoccupied classroom (Fukuchi and Ueno 2004). In the United Kingdom, the Building Bulletin 93 (BB93, 2003) indicates that RT is given in terms of the maximum mid-frequency reverberation time, T mf , the average RT in the 500 Hz, 1000 Hz and 2000 Hz octave bands, and RT should be measured in the unfurnished and unoccupied classroom. ...
Chapter
In every society-past, present and probably also future-, knowledge was, is, and will undoubtedly continue to be transmitted through the process of speaking and listening, i.e., a person transmitting knowledge orally to others who receive it. Notwithstanding current requirements for a variety of knowledge transmission techniques involving multimedia technologies, nothing can replace the teacher-student relationship that is basically involved in classrooms. It is therefore crucial for classrooms to provide optimal conditions for the development of activities inherent to education, which include the quality of classroom acoustics. The quality of transmitted and perceived verbal information is linked intrinsically to the acoustic performance of the room, which in turn involves the observance of several speech quality descriptors-Reverberation Time, Speech Transmission Index, Definition and Centre Time. This chapter on Classroom Acoustics describes the techniques required for in situ measurements of these parameters, which are crucial for verbal communication. These parameters, which are based on national and international technical standards, seek to establish reference values in order to achieve good acoustics in classrooms. Another tool presented is computational simulation, which enables acoustic solutions for classrooms to be tested while still in the design phase, as well as interventions in existing buildings. As a necessary part of the search for optimal classroom acoustics, real cases are presented whose objects of study are university classrooms.
... The recommended NC level for a classroom is NC 25 to NC 30 [18]. For the reverberation time, the recommendation values were different based on difference country or standards with difference derivations [19][20][21]. In overall, these standards or guidelines recommended the reverberation time of unoccupied classroom should be below 0.8 second. ...
Article
Full-text available
Classrooms and laboratories are important spaces that use for teaching and learning process in the school. Therefore, good acoustical performances of these spaces are essential to ensure the speech or message from the teacher can be delivered to the students effectively and clearly. The aims of this study is to determine the acoustical performance of the teaching and learning spaces in public school that situated near to the traffic roads. The acoustical performance of the classrooms and laboratories at Sekolah Menengah Kebangsaan Convent Batu Pahat was evaluated in this study. The reverberation time and ambient noise of these learning spaces which are the main parameters for classroom design criteria were evaluated. Field measurements were carried out inside six classrooms and four laboratories unoccupied furnished according to the international standards. The acoustical performances of the tested learning spaces were poor where the noise criteria and reverberation times inside the measured classrooms and laboratories were higher than recommended values.
... Germany, Japan, the United Kingdom, the United States of America, Portugal and France have specific technical standards for evaluating the RT of classrooms. In Japan, RT values represent the average in 2-octave bands including 500 Hz and 1000 Hz, and RT is measured in the furnished and unoccupied classroom 28 . In the USA, RT is given as the maximum RT for mid-band frequencies of 500 Hz, 1000 Hz and 2000 Hz, and RT is measured in the furnished and unoccupied classroom (ANSI S12.60 29 ). ...
... Various acoustic standards present reference values for the RT that should be observed in classroom design. In Japan, RT values represent the average in 2octave bands including 500 Hz and 1000 Hz, and RT is measured in the furnished and unoccupied classroom 25 . In the U.S., RT is given as the maximum RT for midband frequencies of 500 Hz, 1000 Hz and 2000 Hz, and RT is measured in the furnished and unoccupied classroom 26 . ...
Article
This paper describes a case study about the acoustical quality of classrooms in a public National University relating to the parameter reverberation time (RT). It is shown that, after wrong administrative decisions, classrooms which previously displayed good acoustical quality with respect to RT values, showed a change in this parameter due to a change in the covering of the ceiling. Final RT values after the change in the material covering the ceiling of these classrooms caused them not to fit into the values required by either National or International Standards, or the World Health Organization.
... The standards or guidelines of the countries cited in Table 2 define the RT for the following conditions: a) furnished and unoccupied rooms: Brazil, Japan and the USA; b) unfurnished and unoccupied: United Kingdom. In Japan, 17 RT values are the mean in the two octave bands centered at 500 and 1000 Hz. In the United Kingdom the Building Bulletin BB-93 16 indicates that RT is given in terms of the maximum mid frequency reverberation time T mf , the average RT in the 500 Hz, 1000 Hz, and 2000 Hz octave bands. ...
Article
The acoustical quality of a standard classroom in a public school has been evaluated. This standard is defined as a central circulation aisle with two classrooms on each side, with a total of four classrooms per edification. The measured reverberation times (RT) of the 4 classrooms for a frequency of 500 Hz were: 1.65s (empty classroom); 1.15s (20 students in the room); and 0.76s (40 students). According to WHO recommendations, the ideal RT in classrooms should be around 0.6 s. DIN 18041 establishes an RT between 0.8 and 1.0 s, to allow for adequate intelligibility. Background noise in an empty room was 63.3 dB(A), above the limit established by the Brazilian standard for acoustic comfort, which is 40 dB(A).
... The standards or guidelines of the countries cited in Table 2 define the RT for the following condi- tions: a) furnished and unoccupied rooms: Brazil, Japan and the USA; b) unfurnished and unoccupied: United Kingdom. In Japan, 17 RT values are the mean in the two octave bands centered at 500 and 1000 Hz. In the United Kingdom the Building Bulletin BB-93 16 indicates that RT is given in terms of the maximum mid frequency reverberation time T mf , the average RT in the 500 Hz, 1000 Hz, and 2000 Hz octave bands. ...
Article
The acoustical quality of classrooms in Brazilian public schools is evaluated. Reverberation time (RT) was measured in classrooms according to ISO 3382. Measurements have shown that empty classrooms display an RT of 1.6 s at 500 Hz. Ambient noise of the classrooms was also evaluated according to the Brazilian Standard for Acoustical Comfort NBR 10152 and the British Building Bulletin BB93. The walls separating the corridor and the classrooms have high level louvers, with fixed glass slats which provide a permanent opening for ventilation and illumination, and one door. The measured weighed apparent sound reduction index R'(w) (ISO 717-1) for these walls was R'(w)=13 dB. This is a very low value, when confronted with those demanded, for example, by the German Standards DIN 4109-"Noise Control and Building", and DIN 18041-"Acoustical quality in small to medium-sized rooms" (R'(w)=32 dB). (c) 2007 Institute of Noise Control Engineering.
Conference Paper
Full-text available
Children spend 45-75% of their time in the classroom listening to their teacher and classmates. As current teaching methods have a strong focus on group work activities, contemporary classrooms are prone to high noise levels. Therefore, the classroom acoustic environment needs to be designed appropriately. The AS/NZS2107:2000 standard currently has recommendations for unoccupied classroom ambient noise levels and reverberation times, however, these are not enforced. Furthermore, there are no recommendations for occupied classroom acoustic conditions. Therefore, the aim of this paper was to review current classroom acoustic standards and recommendations around the world, summarise typical noise levels found in classrooms, and provide recommendations on the unoccupied and occupied classroom acoustic conditions needed for children at different ages and children with special educational needs.
Article
Verbal learning is essential on human learning. Good acoustics is an indispensable requirement for verbal learning and therefore vital to all knowledge based societies. Classrooms where most of the verbal learning activities take place, should have good acoustics. Research has shown that in many countries, in different types of educational buildings such as elementary schools, high schools and universities, a great percentage of classrooms has insufficient acoustics. Recommendations for both noise levels and reverberation times, which are the main parameters affecting the acoustical quality of a classroom, have been documented in literature for a long time. However their degree of presence in national and international guidelines, standards and regulations, and more importantly their implementation shows a great variety. In some countries requirements are more compelling and are given as part of a building code, whereas in others they are presented as recommendations or guidelines. This paper presents and compares requirements regarding classroom acoustics in several countries. Requirements will be presented under ambient and equipment noise levels, sound insulation and room acoustical parameters headlines. As there is an increased interest on the subject in several countries, recent changes in some of the national regulations or building codes, will also be mentioned.
Study on acoustical conditions in elementary schools of open-plan type in Japan
  • H Tachibana
  • K Ueno
H. Tachibana and K. Ueno, "Study on acoustical conditions in elementary schools of open-plan type in Japan," Internoise 2002, N323, 324.
Rating of sound insulation in buildings and of building elements -Part 2: Floor impact sound insulation
JIS A 1419-2, "Rating of sound insulation in buildings and of building elements -Part 2: Floor impact sound insulation", 2000.