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Essex Study. Classroom Acoustics:. David Canning London Borough Newham d.canning@ucl.ac.uk. Overview. Purpose of the Essex study Practical aspects of the study Principal acoustic findings. The question posed by Essex CC. Purpose of the Study:
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Essex Study Classroom Acoustics: David Canning London Borough Newham d.canning@ucl.ac.uk
Overview • Purpose of the Essex study • Practical aspects of the study • Principal acoustic findings
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?
Three principles: • Experimental Approach • 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
Classroom Selected • Typical cellular classrooms, typical of the majority of school buildings for children 11yrs – 16yrs in the UK:
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
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.
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
Selection of Groups • 10 teachers • 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
Outcome measures -Occupied Sound Levels, -Signal to noise levels
Principal acoustics findingsAcoustic 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
L90 plotted against RT(reverberation time)Each of the tree classrooms Ultra strict teacher 7 Teachers Control Classroom Ultra relaxed teacher
The significance of acoustic absorbency (short reverberation times)On Functional Signal TO Noise Levels 0.4
Ideal Classroom for Group Work http://eastafrica.usaid.gov/images/Photo.300.1407.aspx