PROCEEDINGS of the
23rd International Congress on Acoustics
9 to 13 September 2019 in Aachen, Germany

The sound environment of German preschools and preschool
teachers’ thoughts about sound generated by children
Saki NOGUCHI1; Hisako YOSHIZAWA2; Masayuki SATO3; Tadashi KONISHI4
1
2

Meiji University, Japan

Heinrich Heine University Düsseldorf, Germany
3
3

Waseda University, JapanTokyo City University, Japan

ABSTRACT
Noticeably, preschool children develop language and communication, so improvement of the preschool’ssound environment is important. Currently, Japanese preschool facilities have experienced problems withnoise. One cause is a lack of sound absorption. Moreover, the loudness of the generated sound is a second
cause because preschool teachers generally believe that children’s voices should not be muted. Therefore,
improvement of sound environment is important and should be approached from both facility design andchild behavior philosophy. In Germany, The German standard (DIN 18041) has necessitated the same levelof sound absorption in the nursery as in elementary schools since 2004. Under the influence of these factors,architectural ideas, such as increasing the equivalent sound-absorption area, are generally seen atpreschools (Kawai et al., 2018). Therefore, we have researched the sound environment at Germanpreschools and preschool teachers’ thoughts about the sound generated by children to identify ways tocreate a more acoustically comfortable learning environment. We observed three preschools and comparedthem to Japanese preschools. It was found that by implementing acoustic improvements in classroom
design and increasing teacher awareness of appropriate sound environment, the noise levels tend to belower. Consequently, it is believed that a proper acoustic environment improves overall awareness, leading
to the creation of a better educational environment.
Keywords: acoustic design, learning environment, noise mitigation, preschool classroom, teacher responses

1. INTRODUCTION
Preschool children generate a remarkable amount of language and communication. Because they
can create noisy environments, preservation of the sound environment in facilities where theyinteract, such as preschools, is an important issue. Currently, Japanese preschool facilities areexperiencing concerns about noise levels that may lead to negative effects on children’s development.
One cause of the excessive noise is a lack of sound absorption in the facility design. Because there isno building standard for acoustic performance in Japanese preschool facilities, many do not containadequate sound-absorbing materials and insulation (1). In addition to physical considerations ofnoise levels in the facility, there is also the social expectation that children should be lively and fullof energy. Preschool teachers tend to have a higher tolerance of noise levels (2) and allow theenvironment to be loud, as to not interfere with the sound freely generated by the children. Therefore,sound environment preservation of preschool facilities requires an approach that addresses both thefacility acoustic environment and the sound generated by children.
On the other hand, the standards in some countries require acoustic performance equal to or better
than that in elementary schools (3). In particular, Germany, which has similar preschool facility
challenges as those of Japan, has found a way to address noise issues by improving both
environmental and social systems. The German standard (DIN 18041) has necessitated the same1

n-saki@akane.waseda.jp
yoshizawa.hisako@gmail.com
3
satomasayuki@waseda.jp
4kmiyabi.cdl@gmail.com
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level of sound absorption in the nursery as in elementary schools since 2004. In addition, DIN 18041
of 2016 also requires better acoustic performance for inclusive education (4). Under the influence of
these factors, architectural ideas, such as increasing the equivalent sound-absorption area, aregenerally seen at preschools (5). On social policy, while noise problems related to children's voices
occurred, a judicial decision has been made that “children's voices are not noise.” This decision has
allowed legal reforms to be made (6) and guarantees the right of children to play freely.
Based on the above considerations, this study researches the actual condition of the soundenvironment in German preschools and teachers’ thoughts regarding the sound generated by children.
It then compares this information with that of Japanese preschools to identify how a moreacoustically comfortable environment can be created.

2. METHODOLOGY
The subjects of this research include three preschool facilities under different management
structures in Dusseldorf, Germany. The building environment is depicted in Fig.1, and thedescription of each facility is shown in Tab. 1. We visited each facility for one day in February 2017
to perform a survey, which included a noise level evaluation and interview with the director of thepreschool. We visited in the morning (10-12 o'clock) to conduct the research.
Preschool A implements a Waldorf style of education. Characteristics of the facility include an
asymmetrically shaped room, wood finishing, cloth often used for decoration, etc. Preschool B is aconverted space located a part of a multi-unit dwelling. A loft and a play corner are installed in eachclassroom. In addition to the classrooms, there are dedicated rooms for activities such as sports andart. A part of the courtyard of the dwelling is used for outdoor play, and the hallway is used for playduring rainy weather. Preschool C is a non-authorized preschool for Japanese children and locatedon the lower floor of a commercial building; this part of the building has been converted for thepreschool classrooms. Most of the preschool teachers are Japanese. Japanese educational activities
and lifestyle culture have been kept in mind, as children in this school eventually return to Japan.

(a) Preschool A(b) Preschool B(c) Preschool C
Figure 1 – Photos of preschool facilities

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Table 1 – Preschool environment descriptions
Number of children [Number ofclasses] / classroom style
Authorized, parent initiative
Single-story wooden building,51 [3] / Multi-age classrooms:
A Kita (parent participation style), dedicated for preschool, adjacent 2–5 years old [1]; 3–5 years old
Waldorf education
to geriatric welfare facility[2]Within concrete square-shaped
Authorized, protestant Kita
80 [4] / Multi-age classrooms:
multi-unit dwelling (RCB (management by Protestant
2–5 years old [1]; 3–5 years old
construction, 1–3F), part of themutual aid organizations)[3]
courtyard used for the playground
Unauthorized, private Japanese
Lower floor of a commercial
105 [4] / Age-level classrooms:
C kindergarten (management bybuilding (RC construction, 1, 2F) 2, 3, 4, and 5 years old [1 each]
Japan, for Japanese children)
Management

Building environment

3. Survey of the sound environment
3.1 Survey method
For the sound environment observations, in order to investigate the actual activity sound, werecorded activity status and generated sounds in the classroom and large indoor space, and on theplayground. A sound level meter microphone (RION NL-42) and recorder (SONY PCM-M10) wereused for gathering noise levels. We set the recording devices in a place that would not disturb theactivities of the children and recorded the sounds for about 2 h. The calibration signal was recordedat the start of the recording for later analysis. A typical observed classroom is shown in Fig. 2. In theanalysis, the frequency analysis of the recorded sound and listening of the generated sound source
were conducted to extract the characteristics of the sound environment of each facility.

Microphone

Fig. 2 – Typical classroom where sound was recorded
3.2

Survey results

3.2.1 Room acoustics at various locations
Based on the interior environment and recorded sound source of the facilities, the state ofreverberation is described. The reverberation time (reverb) was simply analyzed using a “clap”
sound recorded in the classroom of Preschool A and in the hallway of Preschool C.
First, the reverb of the classroom of Preschool A was estimated to be approximately 0.38 s (500Hz) and 0.40 s (1 kHz). The finishing material of the room was wood, and it was believed that asound absorbing treatment had been applied to the ceiling. In addition, many cloth decorations wereused, so we had an impression that the reverb for this room was short. When the sound source forthis room was compared with the sounds emitted in the classrooms of Preschools B and C (i.e.,sounds close to the impulse sound source), the impression was that the reverb was short in thoseclassrooms as well.
Next, the reverberation time of the large indoor space (entrance hall) of Preschool C was found tobe approximately 0.87 s (500 Hz) and 1.23 s (1 kHz). No sound-absorbing material was used at thislocation; the area was large and the ceiling was high. Therefore, the impression of the reverb wasthat it was very long. Because this was a large space, it seemed to be often used for physical exercise
and musical activities. It was feared that such a long sound would interfere with the activity.

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3.2.2 Characteristics of the sound environment during preschool activities
The characteristics of the sound environment during preschool activities were observed, which
included listening to the recorded sound and frequency analysis. First, Tab. 2 shows thecharacteristics of the facility environment and the sound environment.
Table 2 – Sound environment characteristics based on facility environment
Facility environment
Generated sound / Impression of reverb / Noise condition
Wood finishingLots of sound generated from wooden floors, furniture,
Wooden furniture and play equipment
and toys
A Play corner setup
Short reverb
Cloth decoration
Mixing of sounds is small, it is easy to hear
Warm light environment
Play corner setup
Little noticeable soundWooden furnitureSound absorbing material on ceilings of the rooms other
B Loft, mat, and sofa permanent setup
than the staff room and toilet
Additional dedicated rooms for sports or art
Short reverb
Hallway used as play space
Mixing of sounds is small, calm impression
Includes a hallway and a multipurpose spaceChildren's voices are the main sound source
C Room configuration changes based on group Short reverb in classrooms, long reverb in hallactivities
Impression that sound was mixed overall
Play corners were always set up in the classrooms of Preschools A and B; in Preschool C, only
desks and chairs were included, and the furniture was moved around according to each activity. In
terms of play equipment, furniture, and materials for decoration, the classrooms in each facility
differed. This is likely due to the differences in education approaches. Regarding generated sound,
only Preschool C emitted loud sounds all at once in the classroom; this might have been duringgreetings when all the children used loud voices, teachers making loud sounds or playing music, etc.
In contrast, there were no situations where particularly loud sounds or voices were used in
Preschools A and B.
Next, the sounds during the activity are described. In the analysis of sound pressure level, we
calculated the equivalent continuous sound level every minute (L eq,1min ), listened to the recordings,
and classified which activity each data element corresponds to. Fig. 3 shows the analysis results of
L eq . The analysis time is the energy average of the sound pressure level of each activity time. The
sound environment characteristics summarized by listening are given in Tab. 3. In order to compare
these results with those of preschools in Japan, the case in Japan (Preschool D) is also described. The
reverberation time in Preschool D was approximately 0.78 s (500 Hz) and 0.81 s (1 kHz). Note that
this reverberation time was longer than Preschool A.
Table 3 – Sound environment characteristics based on activity
Activity

Sound environment characteristics
A, B: Calm play with little movement
Free activity in
C: Craft scene, children are working while talking
classroomC, D: Many children’s voices
A: (1) Generally quiet, (2) Noise level goes up following the loud voice of one
Free activity on the
disabled childplayground
B: Children play actively and are relatively lively, influence of building reflections
is inferred because of courtyard setting
B: Voices only, children sing quietly
Singing
C, D: Includes piano accompaniment, C’s children participate in lively singing
Common: A generally quiet environment compared to other activities for all
Difference: The difference between A, B, and D is the children’s voices (1–2 kHz
Reading picture bookoctave band).
A, B: The voice of the teacher is primary, quieter sound environment

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 90
90
	
 
80
80
	
 
	
 70
70
	
 
60
60
	
 
	
 50
50
	
 
40
40
	
 
	
 

C:
5 years, 25 children, 15 minC:5[25,15min]B:
3–5 years, 21 children, 30 min
B:3-5[21,30min]D:
5 years, 25 children, 15 minD:5[25,15min]

90
90

SoundPressure
Pressure
Level
Sound
Level
[dB][dB]

Sound
Level[dB][dB]
SoundPressure
Pressure LevelA:
3–5 years, 17 children, 30 min
A:3-5[17,30min]

31.5
63 125250 500
500 1k1k 2k31.5 63
125 250
2k 4k
4k 8k
8k OA
OA A-W
A-w
Centerofof1/1
1/1 Octave
Octave Frequency
Band[Hz][Hz]
CenterFrequency
Band

Sound
Pressure
Level
Sound
Pressure
Level[dB][dB]

40
40

	
 

B: 2–5 years, 17 children, 9 minB:2-5[17,9min]
D:5[25,8min]
D: 5 years, 25 children, 8 minC:
3–5 years, 20 children, 5 minC:3-5[20,5min]

31.5 63
63 12531.5
125 250250 500
500 1k1k 2k
2k 4k
4k 8k8k OA
OA A-W
A-w
Centerofof1/1
1/1Octave
Octave Frequency
Band
[Hz]
CenterFrequency
Band
[Hz]

D:
3–5 years, 100 children, 1 min
D:3-5[100,1min]

70
70
60
60
50
50
40
40

31.5 63
63 125250 500
500 1k1k 2k
31.5
125 250
2k 4k
4k 8k
8k OA
OA A-W
A-w
Center of
Frequency
BandBand[Hz] [Hz]Center
of1/1
1/1Octave
OctaveFrequency(b) Free activity on the playground
	
 
80
80

Sound
Pressure
Level
Sound
Pressure
Level[dB] [dB]

	
 
	
 
80
80
	
 
	
 
70
70
	
 
60
60
	
 
	
 
50
50
	
 

A(2):
3–5 years, 17 children, 5 min
A(2):3-5[17,5min]8080(a) Free activity in the classroom
90
90

A(1): 3–5 years, 17 children, 8 min
A(1):3-5[17,8min]
B: 3–5-years, 80 children, 40 min
B:3-5[80,40min]

A: 2–5 years, 17 children, 5 minA:2-5[17,5min]
D:5[25,4min]
D: 5 years, 25 children, 4 min

B: 3–5 years, 20 children, 12 minB:3-5[20,12min]

70
70
60
60
50
50
40
40

	
 3030

31.5 63
63 125250 500
500 1k1k 2k
31.5
125 250
2k 4k
4k 8k
8k OA
OA A-W
A-w
CenterFrequency
Band
Centerofof1/1
1/1 Octave
Octave Frequency
Band[Hz][Hz](c) Singing(d) Reading picture bookFigure 3 – Sound pressure level for each activity	
 It can be pointed out that the sound pressure levels are higher in Preschool C and in Japanesepreschools than in Preschools A and B. From the generated sound observations, it was found that thecenter of the liveliness was the children's voices (1–2 kHz octave band) and sounds of toys (250–500
Hz octave band).
During the free activity in the classroom, there was a tendency of each person’s voice becoming
louder in Preschool C because there were a large number of children in the room, population density
in the facility was high, and nearby voices were mixed. In addition, it is believed that this tendency
became louder because the reverb of Preschool D was long. On the other hand, at Preschools A andB, children were also talking, but they had an environment where they could talk independently,
without mixing with other play and talking voices; this prevented their voices from becoming
synergistically loud. Consequently, in Preschools A and B, the level of the noise and the voice (1–2
kHz octave band) were lower than those in Preschools C and D, and there was a calm impression.
During the free activity on the playground, the sound environments of Preschools B and D weresimilar, and the sound pressure level tended to increase as the children played actively. In Preschool
A, the number of children was small, and the surrounding environment was quiet; therefore, it alsotended to be quiet outside. During playing time, one disabled child used a loud voice for about 5 min(Fig.3 (b): A(2)); at that time, the noise level was temporarily raised to the same level (L Aeq ) as in
Preschools B and D. However, the level of the generated sound itself was low, and the calm
environment was maintained.
During the singing activity, there was a noticeable difference between Preschools B and C. In
Preschool C, a piano was used, and everyone was singing loudly. In Preschool B, accompanimentmusic was not used, and the teacher sang quietly in the circle with the children. Comparing with thecases in Japan, Preschool C seemed to enjoy the songs at the same level as Preschool D, whilechildren at Preschool B sang calmer than Preschool C and D.
During the reading picture book activity, the environment for listening quietly was similar. The
difference was the amount of the children's vocalization. In Preschools A and B, the voices of thechildren were low and the teacher's voice (500 Hz, 1 kHz octave band) was the most prominent.
However, in Preschool D, the level of the children’s voice (1–2 kHz octave band) was high, and5922

multiple children were actively responding at the same time.
The above observations suggest that the generated sound differs depending on the style ofeducation, such as how the preschool teachers relate to the children, the number of children, and thepreschool activities. A long reverb in the facility amplifies the sound level; however soundabsorption design makes it possible to avoid the mixing of sounds to maintain a calm environment.
For comparison, sound absorption in building design has been implemented in Germany, whereas it
has not been implemented in Japan. Therefore, there are still many preschool facilities in Japan
where the reverb is long. Because of this and the difference in the style of education, it is believedthat German preschools tend to have a quieter and calmer environment than Japanese preschools.

4. Preschool teachers’ thoughts about sound generated by children
4.1 Survey method
To investigate preschool teachers’ responses to sound generated by children, an interview was
conducted with one director at each facility; these were semi-structured interviews with twointerviewers and one interpreter. The questions involved considerations about early childhood
education, such as educational philosophy, current activity status, sound environment during theactivity, behavior of children, influence of neighborhood, and associated issues. Example questions
on the sound environment during the activity are given in Tab. 4.
Table 4 – Example questions on the sound environment during activity
1) The sounds that the teachers are concerned
Are there any scenes where the sounds concern?
2) Voice of children
Have you ever felt that children are noisy? / How do you respond when you feel that children are
noisy? / Do children ever shout or use loud voice during the activity?
3) Instruction about children’s voicing
Do you teach children how to vocalize or sing? / When do you feel that children's vocalization is aproblem? How do you respond then?
4) Vocalization of the preschool teacher
Is there anything that you take care about with respect to vocalization? / Have you ever had specialized
training for vocalization? / What kind of education did you receive on educational behavior?
5) Comparison with Japan
Have you ever been concerned about with the reverberation of the classroom? / Do you adjust theenvironment considering the sound environment?
4.2 Survey results
The result of the interview is given in Tab. 5.
Table 5 – Sounds that teachers are concerned about and their responses◇The sounds that teachers are concerned about▲Sounds pointed out by outsider◎Educational behavior＊Environmental modifications◎Humming with commonly known songs to encourage◇Play sound when the children are not calm
children’s independent behavior (e.g. cleaning up)◇Tidying up time
◎Talk privately to bustling children
A ◇Behavioral sounds of autistic children◎Keep teacher’s calm
◇Sound of objects (especially the sound of◎Do not stop the behavior of disabled children
wooden chairs and toys hitting wood floors)＊Set a calm lighting environment◎Teachers wait for lively children to notice group◇Sound during indoor play when stress tends
behavior first and talk to them individually if needed
to build up, such as when it rains＊Modify the hallway ceiling with sound-absorbing
B▲Active play sound when outside playing
material so that it can be used as a active play space(voices, laughter, etc.)＊Apply soundproofing measures to wheels of
playground equipment (bicycles, etc.)◎Respond individually to crying children◇Crying voices
C◎Talk with the children to calm them down when
▲Excited voices when carrying pool outdoors
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At Preschool C, there was a tendency to generally accept the voice levels of the children, which iscommon in Japanese early childhood educational culture (2). In contrast, in Preschools A and B, it
appeared that teachers thought that too much liveliness was an issue. In these preschools, teachers
seemed to be involved with children who are talking loudly, such as waiting for their awareness ortalking personally. In other words, even if the noise was caused by a child's voice, it was understoodthat teachers treated the voice as "noisy" when it was inappropriate; they would then show the childthe desirable behavior.
At Preschool B, there was a case where teachers suggested modifying the sound absorption
specification of the hallway so that it could be used for more noisy activities. Such vocal examples
are rarely found in Japan. This indicates that the teacher recognized the importance of soundabsorption. It was believed that this recognition might be because this teacher had experienced theeffectiveness of high sound absorption efficiency and understood how a noisy environment can
influence educational activities.
At Preschool A, which carries out Waldorf education, the importance of educator behavior, suchas, “We try to create a sound environment that sounds can be transmitted as such,” or “Teachers
should first appreciate the importance of remaining calm when speaking to children,” was discussed.
The sound environment of Preschool A was calm, and it was an environment where each child's
voice could be heard without sound mixed. It has been suggested that such environment helped theteacher to work better with children and deepen their play.
From these observations, it was found that teacher awareness of noise and their responses to thesounds generated by children differ between Germany and Japan. It is also believed that in Germany,
there is a purposeful educational intent in controlling sound levels in the classroom so as to improve
collaboration with the educational environment and other children.

5. CONCLUSIONSIn this study, we investigated the sound environment and teachers’ thought about sounds emitted
by children in German preschools to identify how a more acoustically comfortable environment canbe created. The German preschools were found to differ from Japanese preschools in aspects such as
facility acoustic design, social systems, and early childhood educational culture. First, as describedin our previous study (5), Germany has implemented a sound-absorption design requirement forindoor activity spaces in preschools. Because of this, not only acoustic experts but also preschool
teachers recognize the need for sound absorption in teaching spaces. This recognition may be
because noise disturbances and the associated negative effect on children’s activity are more
noticeable once a calm, quieter, and higher-efficiency environment becomes the norm. An
educational environment with better sound environment also allows the preschool teacher to be moreaware of the disturbance by noise and long reverberation, and can help them to adjust their behavior
appropriately. These approaches to mitigating preschool noise in areas of facility design, playequipment, furniture, etc. as well as teacher responses to sounds generated by children were
implemented in the German preschools. As a result, the sound environment in the Germanpreschools was quieter.
This study suggests that differences in preschool environmental standards and teacher behaviors
are driven by differences in the cultural views of education and children; ultimately, this causes
noise levels in the preschools to be different. This study also suggests that a proper acoustic
environment improves human awareness and leads to the creation of a better educational
environment.
Finally, in Germany, while the voices of children are legally not considered noise, this does notmean that disruptively loud voices should be accepted; it only means that the normal activities ofchildren (and associated noise) should not be limited. That the liveliness of the children should be
tolerated was likely determined by professionals of early childhood education. Therefore, to create abetter sound environment for children in Japanese preschools, we are now working on thedevelopment of acoustic performance standards. Future research is expected to include expanding
discussions on the sounds emitted by children in the field of early childhood education.

ACKNOWLEDGEMENTS
We would like to thank the German and Japanese preschool teachers for their cooperation in thissurvey. This study was supported by the research grant of K. MATSUSHITA FOUNDATION

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(16-586) and JSPS KAKENHI Grant Number JP18K13127.

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3. K. Kawai. Toward acoustical well-being in childcare facilities: Existing regulations and guidelines inWestern countries and recent initiatives in Japan. The Journal of the Acoustical Society of Japan, 72(3),160-165, 2016. (in Japanese).
4. C. Nocke. DIN 18041 - a German view. Proceedings of Euronoise 2018, pp.1033–1038, Crete, 2018.
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