Transcript Improving the acoustic environment of schools for pupils

Improving the acoustic environment
of schools for pupils and teachers
Bridget Shield & Anne Carey
London South Bank University
Julie Dockrell & Kate Rigby
Institute of Education, University of London
LARCI seminar
Research for Education - Making a
Difference
10 November 2005
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Outline of talk
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Acoustic requirements for classrooms
Background to EPSRC project - previous research
EPSRC project - aims and methodology
Acoustic surveys of classrooms
Remedial acoustic treatments to classrooms
Teachers’ voice levels
Amplification in the classroom
– installation
– benefits
• Summary and conclusions
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Acoustic requirements for classrooms
• To provide good listening and speaking
conditions a classroom must have
– Low background noise
– Short reverberation time
– Good sound insulation
• between classrooms to minimise transmission of
classroom noise
• of external façade to minimise intrusion of external noise
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Building Bulletin 93 (DfES, 2003)
Acoustic design of schools
• School buildings built
since 2003 must comply
with the Building
Regulations
• Legal requirements for
acoustic design of new
schools specified in
Section 1 of Building
Bulletin 93
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Building Bulletin 93 (DfES, 2003)
Acoustic design of schools
• Indoor ambient noise levels
• Airborne sound insulation
• Impact sound insulation
• Reverberation time
• Sound absorption in
corridors and stairwells
• Speech intelligibility in open
plan spaces
DfES kept informed of results of
EPSRC project which will inform
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any revision of BB 93
Two major research projects on
classroom acoustics
• The effects of noise on the attainments and cognitive
performance of primary school children
– Department of Health/DEFRA 1999-2001
• Acoustic design guidelines and teacher strategies for
optimising learning conditions in classrooms for
hearing and hearing-impaired children
– EPSRC (EQUAL) 2002 - 2005
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Background - previous study
Methodology
• Noise surveys outside 142 primary schools in 3
London boroughs
• Noise surveys inside 140 classrooms in 16
schools in two boroughs
• Questionnaire survey of all Year 2 children in one
borough (N>2000) and their teachers (N>50)
• Comparison of noise levels with SATs results
• Experimental testing of mainstream and SEN
children in typical noise conditions
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Background - previous study results
• Children are exposed to higher noise levels at school than
recommended by BB 93 and WHO
• Children are aware of noise and annoyed by specific noise
sources
• Ease of listening in the classroom is related to external
noise levels
• Exposure to noise affected performance on academic
tasks
– Classroom babble affects performance on verbal tasks
– External environmental noise affects non-verbal tasks and speed of
processing tasks
– Children with special educational needs are differentially affected
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• Majority of teachers experience voice and throat problems
Effects of noise on Key Stage 2 SATs
External noise (142 schools)
Internal noise (16 schools)
Background noise level v English score
100
100
KS2 English score %
KS2 Maths score %
Maximum noise level v Maths scores
80
60
40
20
80
60
40
20
20
40
60
80
100
40
45
50
55
dB LA90
60
65
dB LAmax
Results hold when data corrected for socio-economic factors
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Effects of noise on speed processing task
Changes in test scores in noise
45
40
35
30
25
20
15
10
5
0
Quiet
Babble
Babble + env
noise
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Effects of noise on children with special
educational needs
Results of experimental testing
Change in spelling scores
Change in reading scores
40
35
30
25
20
15
10
5
0
12
10
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SEN
Typical
SEN
Typical
6
4
2
0
quiet
noise
quiet
noise
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Acoustic design guidelines and teacher strategies for
optimising learning conditions in classrooms for
hearing and hearing-impaired children
Aims of EPSRC EQUAL project
• To identify those acoustic parameters that are most
applicable to children’s hearing and listening in
classrooms
• To investigate ways of improving the acoustics in
classrooms
• To investigate the use and effectiveness of classroom
amplification systems
• To investigate the effects of acoustics on teachers’ voices
• To develop new word tests for hearing and hearing
impaired children
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Acoustic design guidelines and teacher strategies for
optimising learning conditions in classrooms for
hearing and hearing-impaired children
Aims of EPSRC EQUAL project
• To identify those acoustic parameters that are most
applicable to children’s hearing and listening in
classrooms
• To investigate ways of improving the acoustics in
classrooms
• To investigate the use and effectiveness of classroom
amplification systems
• To investigate the effects of acoustics on teachers’ voices
• To develop new word tests for hearing and hearing
impaired children
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Acoustic design guidelines and teacher strategies for
optimising learning conditions in classrooms for
hearing and hearing-impaired children
Methods used in EPSRC EQUAL project
• 39 mainstream and special schools in London, Herts,
Berks, Hants
• Acoustic surveys of 55 classrooms in 25 schools
• Measurements of voice levels of 36 teachers
• Study of installation and use of amplification systems
(SFS) in ~20 schools
– Questionnaire surveys of children with and without SFS
– Cognitive testing of children with and without SFS
– Structured observation of children with and without SFS
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Acoustic survey of 55 classrooms:
reverberation times
Unoccupied reverberation time (Tmf) in 55 classrooms in 25 schools.
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1.9
1.8
1.7
1.6
Reverberation time, Tmf (s)
1.5
1.4
1.3
1.2
1.1
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
36 11 13 35 12 5 53 34 7 52 43 14 15 42 41 27 20 28 29 46 49 24 25 22 32 31 26 30 4 45 55 54 16 2 3 17 48 6 38 1 8 47 44 40 10 39 50 18 51 19 23 9 21 37 33
Classroom identification number
Untreated classrooms
Treated classrooms
18 out of 44 untreated rooms meet BB 93 criterion15
All treated rooms meet criterion
Teachers’ voice levels
36 teachers voice levels (4 male, 32 female) at 1.0 m
84
82
80
78
76
LAeq at 1.0m, dB(A)
74
72
70
68
66
M
64
62
F
60
58
56
54
52
50
15 34
8
5
4
20 10 13
6
2
9
18 26
3
21 17
1
27 30 16 11 14 31
7
29 33 36 24 32 25 22 19 12 23 35 28
Teacher identification number
female
male
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What can be done to improve the acoustic
conditions for teaching and learning?
• For teachers
• For children
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–
–
–
–
mainstream
with permanent hearing loss
with temporary hearing loss
with language problems
with attention difficulties
Two approaches investigated:
•Increasing acoustic absorption to reduce reverberation time
•Using amplification/sound field systems in the classroom
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Effectiveness of acoustic treatment
Acoustic absorption can be added to the ceiling (as
here) or to the ceiling and walls
No absorption: RT = 1s
With absorption: RT = 0.5s
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Effectiveness of acoustic treatment
Measurements in 7 untreated and 6 matched treated classrooms
1.2
Spatially averaged reverberation time, T30 (s)
1.1
1.0
0.9
0.8
0.7
Average of 7 treated
classrooms with
standard deviation bars
0.6
Average of 6 untreated
classrooms with
standard deviation bars
0.5
0.4
0.3
0.2
0.1
0.0
100
1000
Frequency (Hz)
10000
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Amplification in the classroom
What is a Sound Field System (SFS)?
• A SFS is essentially a simple speech reinforcement
system used by the teacher.
• Three main types:
- 4 small moving coil loudspeaker
- single column loudspeaker
- multiple flat panel (DML) in ceiling
• Systems usually consist of boom or collar mounted
directional radio mic & transmitter, radio mic receiver,
mixer/amp & loudspeakers.
• Typical price £1000 - £1500 per system.
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Amplification in the classroom
Why are SFS installed?
• To provide all pupils in the classroom with equal speech
signal from the teacher
• Installed in classrooms where there is a hearing impaired
child
• Installed for use by a teacher with voice problems
• Systems are installed: for individual pupils, to improve
acoustics by the school, or in a blanket manner by LEA.
• General misconception that SFS solve all acoustical
problems
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Amplification in the classroom
Where are SFS installed?
2.0
Some
SFSsystems
installedinstalled
across in
very
large
suitable
small
rooms
rooms
rooms
withand
long
with
low
RT
whole
range
of may
–background
potentially
be workingmake
noise
well and
things
– any
classrooms
measured
makingpoint?
worse
a difference
1.9
1.8
1.7
1.6
Reverberation time, mf
T (s)
1.5
1.4
1.3
1.2
1.1
1.0
30.3dB(A)
0.9
0.8
37.4dB(A)
0.7
37.3dB(A)
0.6
0.5
31.9dB(A)
0.4
0.3
36.8dB(A)
0.2
0.1
0.0
50
75
100
125
150
175
200
225
250
275
300
325
350
375
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Estimated volume (m )
Untreated classrooms
Treated classrooms
Classrooms with SFS
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400
Amplification in the classroom
SFS were not used in about half of the
classrooms in which they were installed
Sound field systems can only be used successfully if
• Acoustic conditions in the classroom are suitable
• They are installed correctly, in appropriate places in
the classroom
• They are installed in consultation with the teachers
who will be using them
• Teachers are given training in their use
• If they work!
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Examples of poor installation/communication
The loudspeakers have been
installed in areas where class
teaching does not take place
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Example of poor training of the teacher
The loudspeakers have been
decorated for Christmas!
Of teachers surveyed
• 56% not given any training in use
of systems
• 63% not consulted about placing
of systems
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Evaluation of sound field systems
• Schools in Hertfordshire and London
• Effects on children’s listening
– questionnaire survey of children in mainstream (Nq=1396) and
special schools (Nq=128) before and 6 months after
installation
• Effects on children’s behaviour
– Structured observation of pairs of hearing and hearing
impaired children in 9 classrooms with and without SFS
• Effect on children’s performance - SFS on/off
– testing of 380 children (24 with SEN) over 3 week period
– spelling, oral comprehension, speed of processing
• Effect on children’s learning - 6 months after
installation
– testing of 280 children (41 with SEN) before and after
– spelling, oral comprehension, speed of processing, reading,
maths
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Evaluation of sound field systems - impact
on listening
• Children in SFS classrooms reported improvements in
hearing teacher in 3 out of 8 situations when teacher is
speaking
– writing on board
– working in groups
– children making noise outside classroom
• No changes for hearing impaired children
– small sample and possible technical difficulties
• Children in special schools reported improvements when
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–
–
–
cannot see teacher’s face
writing on board
moving around classroom
children making noise outside classroom
Benefits in hearing teacher for majority of children27
Evaluation of sound field systems observational results
• No changes between classrooms with and without SFS in
–
–
–
–
adult involvement
type of task performed by children
type of sound made by children
underlying teaching and learning activities
• In SFS classrooms
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–
–
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children's hands raised less often
children more attentive
children respond more quickly to teacher
children less distracted by external noise
Beneficial effects for all children
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Evaluation of sound field systems - effect on
children’s performance and learning
Performance (SFS on/off)
• Improvements in spelling for all children
– no change in comprehension and speed of processing
• Improvements in spelling and comprehension for SEN
children
– no change for speed of processing
• Effects greater for SEN children
Learning (changes after 6 months)
• No changes in spelling and maths
• Significant improvements in comprehension and speed of
processing
Improvement in processing oral input, particularly29
for children with additional learning needs
Summary and conclusions
• The acoustic conditions in the majority of existing
classrooms do not meet current regulations
• Reducing noise and reverberation would benefit children’s
learning and teachers’ health
• Acoustic treatments can be applied to remedy the situation
• Amplification in the classroom can improve the listening
and learning situation for mainstream children and those
with additional learning needs
• Amplification is not a remedy for poor acoustics
• In order to be used successfully amplification must be
installed
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–
–
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in classrooms which are acoustically suitable
in appropriate positions in the classroom
in consultation with the teacher
with adequate training of teachers
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Current and further EPSRC research
• The acoustics of open plan classrooms
(LSBU, EPSRC studentship, 2003 - 2007)
• Modelling performance of SFS
(LSBU, EPSRC studentship, 2005 - 2008)
• The acoustic design of secondary schools
(LSBU, IoEd, Univ of Salford, new application)
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Help needed
• Access to schools
• Opportunities to do ‘before’ and ‘after’ testing
(acoustic and psychological) where remedial
treatment/structural alterations planned
• Access to classrooms to test new word test
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Acknowledgements
This work has been funded by the
Engineering and Physical Sciences
Research Council.
Contacts
Julie Dockrell:
[email protected]
Bridget Shield:
[email protected]
LARCI seminar
Research for Education - Making a
Difference
10 November 2005
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