PowerPoint Presentation

Essex StudyClassroom Acoustics:

David CanningLondon Borough Newham

d.canning@ucl.ac.ukOverviewPurpose of the Essex studyPractical aspects of the studyPrincipal acoustic findingsThe question posed by Essex CCPurpose 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?

3

Introduction

Introduction

Three principles:Experimental ApproachWe chose to design an approach that would be useful in determining causalityGeneralisableChange one variable onlyStaff and children blind to conditionAnalysis of acoustic data will be carried out blind to the conditionAchievableGiven 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: 6Classroom SelectedTypical cellular classrooms, typical of the majority of school buildings for children 11yrs 16yrs in the UK:

7Practical Aspects of the studyChose one curriculum area: Mathematics.4 Identical classroomsSound 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 weekendStaff willing to tolerate and eventually ignore measurement equipment, observation and repeated questionnaires over a period of at least 6 monthsMathmatics, or math, one of the most studied subject areas and most consistently taught.8

Classroom Acoustic TreatmentBeforeAfterSuspended ceiling added.Acoustics Tiles and Wall Panels.New lights and a coat of paint to all rooms.Hard walls and ceiling. Windows on two sides.Carpet bonded to concrete floor.Area = 50sqm9Selection 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

10Schedule of Room TreatmentsExperimental ConditionBritish Association of Teachers of the Deaf (batod)Rt 0.9s mid frequencies)Pre test (all untreated)Classrooms A,B,C& DPhase 1Classroom AClassroom BClassroom CClassroom DPhase 2Classroom CClassroom AClassroom BClassroom DPhase 3Classroom BClassroom CClassroom AClassroom D11Selection of Groups 10 teachers8 Classes taught exclusively in one of the rooms3 of the 4 classrooms were predominantly used by the same teacherTeacher class combinations10 teacher and class combinations were included in the studyGroups included grades 7 (11yrs) to 10 (14yrs)Top, middle and bottom ability setsChildren 400 children included in the studyIncluding 17 children with hearing impairment

12Outcome measures-Occupied Sound Levels, -Signal to noise levels 13Principal 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 requirements0.40.814

L90 plotted against RT (reverberation time)Each of the tree classroomsUltra strict teacherUltra relaxed teacher7 TeachersControl Classroom15Predictor Importance

16Predictor Importance

65dB exceedence level

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

0.419Pupil views

20

http://eastafrica.usaid.gov/images/Photo.300.1407.aspxIdeal Classroom for Group Work