1. Essex Study Classroom Acoustics: David Canning London Borough Newham

2. Overview Purpose of the Essex study Practical aspects of the study
Principal acoustic findings

3. The question posed by Essex CC
Purpose of the Study:
How should we refurbish mainstream classrooms so that they are acceptable listening environments for hearing impaired children.
Supplementary questions:
What is the impact of modifying the physical acoustical performance on the occupied class engaged in learning?
Is there a measureable acoustic impact?
Is there an impact on teaching and learning?
-If there is an impact, then how does this information contribute to the specification and design of teaching spaces?

4. Introduction

5. Introduction

6. Three principles: Experimental Approach Generalisable Achievable
We chose to design an approach that would be useful in determining causality
Generalisable
Change one variable only
Staff and children blind to condition
Analysis of acoustic data will be carried out blind to the condition
Achievable
Given all the constraints, time, possible disruption, cost, equipment and support from the school and LEA.s
We decided to undertake an experimental approach to answering these questions:

7. Classroom Selected
Typical cellular classrooms, typical of the majority of school buildings for children 11yrs – 16yrs in the UK:

8. Practical Aspects of the study
Chose one curriculum area: Mathematics.
4 Identical classrooms
Sound treatments that visually as similar as possible. The school kindly redecorated the rooms.
Ability to change the acoustic performance of all classrooms in the study over a weekend
Staff willing to tolerate and eventually ignore measurement equipment, observation and repeated questionnaires over a period of at least 6 months
Mathmatics, or math, one of the most studied subject areas and most consistently taught.

9. Classroom Acoustic Treatment
Before
Hard walls and ceiling. Windows on two sides.
Carpet bonded to concrete floor.
Area = 50sqm
After
Suspended ceiling added.
Acoustics Tiles and Wall Panels.
New lights and a coat of paint to all rooms.

10. Selection of Acoustic Materials
Acoustic panels absorb sound energy.
The nature of the material used, and the manner in which is used all have an impact on the absorption characteristics

11. Schedule of Room Treatments
Experimental Condition
British Association of Teachers of the Deaf (batod)
Rt <=0.4sec 125Hz – 4Khz
BB93 classrooms designed for use with HI
Mid Frequency
(500Hz – 2Khz) mean = 0.4sec
BB93
(500Hz – 2Khz) mean = 0.8sec
Untreated
(Rt > 0.9s mid frequencies)
Pre test (all untreated)
Classrooms A,B,C& D
Phase 1
Classroom A
Classroom B
Classroom C
Classroom D
Phase 2
Phase 3

12. Selection of Groups 10 teachers Teacher class combinations Children
8 Classes taught exclusively in one of the rooms
3 of the 4 classrooms were predominantly used by the same teacher
Teacher class combinations
10 teacher and class combinations were included in the study
Groups included grades 7 (11yrs) to 10 (14yrs)
Top, middle and bottom ability sets
Children
400 children included in the study
Including 17 children with hearing impairment

13. Outcome measures -Occupied Sound Levels, -Signal to noise levels
Room
Unoccupied Physical Acoustics:
Rt, EDT, C50 etc
Functional Acoustics
Signal to Noise measurements
sound levels
Teacher and Child ratings
LIFE UK
Hearing performance:
Speech discrimination
Interviews and observations
Expert panels

14. Principal acoustics findings Acoustic treatment and classroom noise
Very significant changes in occupied sound levels:
17dB from untreated to highest level of treatment
(1.2 s to 0.4s)
9dB Reduction in Background Noise from current standard to proposed standard for children with ‘special hearing requirements’
0.4
0.8

15. L90 plotted against RT (reverberation time) Each of the tree classrooms
Ultra strict teacher
7 Teachers
Control Classroom
Ultra relaxed teacher

16. Predictor Importance

17. Predictor Importance

18. 65dB exceedence level

19. The significance of acoustic absorbency (short reverberation times) On Functional Signal TO Noise Levels
0.4

20. Pupil views

21. Ideal Classroom for Group Work