Simon Smith (Sweyne Park School) – photo by Martin Arvebro
A workshop regarding open plan office acoustics was held at the Ecophon International Acousticians’ Seminar, in Båstad, Sweden, Sept 22nd.
An opening lecture to introduce the workshop was “Acoustics in my School” (Essex Study) by Simon Smith – Learning Environments Manager, Sweyne Park School, Essex
A total of four presentations were held and discussed in the workshop that followed:
Educational premises (school acoustics): Workshop Moderator – Andrew Parkin (Cundall Acoustics)
David Canning – London Borough of Newham. UK
Essex Study
Bridget Shield – Professor of Acoustics, LSBU. UK
Understanding acoustics in open & semi open learning spaces
Monika Rychtarikova – Katholieke Universiteit Leuven, BelgiumInstitute of Acoustics, RWTH Aachen, Germany
Calculating the Optimum Reverberation Time and Absorption Coefficient for Good Speech Intelligibility in Classroom Design Using U50
Lennart Nilsson – Akustikmiljö AB, Huddinge/Stockholm, Sweden
Low frequency problems in classrooms
David Canning
The Essex Study
David Canning – London Borough of Newham. UK
Several years ago Essex County Council in the UK had faced repeated challenges to the working (functional) acoustic conditions in their schools. One school in particular served as a resourced provision for hearing impaired children. This school had been judged as an outstanding school by Independent Inspectors and it had considerable experience of educating hearing impaired children. The school was an unexceptional building, typical of many in the UK. Most of the teaching took place in virtually identical classrooms each with a volume of about 150 cubic metres. The challenge to the County Council was to create an environment that would meet the auditory needs of hearing impaired children in a working school. They had to find a solution that would be cost effective, and must not be detrimental to teachers or other children.
In order to identify the most suitable acoustic conditions a double blind counterbalanced controlled experimental design was adopted. The simplicity of the design was supported by considerable goodwill and intense periods of refurbishing classrooms at times when neither teachers not students would be in school. During the 6 month experimental period, three identical classrooms received different sound treatments in such a way that they appeared visually the same and a fourth was left untreated. Using a latin square design, the sound treatments were rotated between classrooms at appropriate periods and extensive performance measures were obtained for more than 100 lessons. Both qualitative and quantitative measures were obtained.
This workshop will present some important findings quantitative and qualitative findings the impact of reverberation time on working noise levels and signal to noise levels as measured at the children’s ears. It will also look at the impact of teaching style and class size on functional acoustics.
Bridget Shield
Understanding acoustics in open and semi-open learning spaces
Bridget Shield, Professor of Acoustics, LSBU. UK
Open plan classrooms became popular in the 1970s in Europe and the USA in response to progressive educational movements, however their use was discontinued owing mainly to problems of noise and visual intrusion. In the 21st century educational and architectural trends are leading to a resurgence of open plan design, with many schools incorporating large open areas and atria intended to accommodate shared teaching space.
This presentation will report the results of a large scale, detailed acoustic survey of semi- open plan primary school classrooms in the UK, which have enabled acoustic design guidelines to be developed to ensure good listening conditions. However current acoustic and questionnaire surveys of secondary schools suggest that, even when open plan spaces comply with current acoustic performance standards, students have difficulty hearing their teachers in such spaces. The presentation will conclude by presenting interim results from the current surveys which raise questions concerning appropriate guidelines for large open learning spaces in secondary schools.
Monika Rychtarikova
Calculating the Optimum Reverberation Time and Absorption Coefficient for Good Speech Intelligibility in Classroom Design Using U50
Monika Rychtarikova, Katholieke Universiteit Leuven, BelgiumInstitute of Acoustics, RWTH Aachen, Germany
Acoustical comfort in general, and the quality of speech transmission from teacher to students in particular, are crucial in determining the quality of educational processes in schools. The acoustical treatment of interior surfaces, the sound insulation of surrounding constructions, the vocal capacity of the teacher, student activity noise, children’s abilities to hear and concentrate and the educational circumstances, are among the many factors in the
complex mechanism of speech understanding. Managing the rich variety of measures for optimising classroom acoustics demands a multidisciplinary approach.
In this article we propose a predictive model for speech intelligibility, as expressed with the parameter U50, based on objective acoustical values, i.e. the reverberation time RT, signal-to-noise ratio SN, and the relative proportions of sound arriving early and late at the listener.
The possible additional need for minimum RT values is also investigated in relation to the phenomenon of ’overdamping‘ in classrooms.
Lennart Nilsson
Low frequency problems in classrooms
Lennart Nilsson, Akustikmiljö AB, Huddinge/Stockholm, Sweden
Almost all classrooms have a reverberation time that increases dramatically at lower frequencies.
Normally the specified reverberation time is 0,5 seconds, which means a mean value between 250 and 4000 Hz. At lower frequencies it is not specified.
At 125 Hz it often reach 1,0 seconds and at 63 Hz it often goes beyond 2,0 seconds.
What happens is that we get a rather big masking effect and because of this the recommendation in the Swedish standard is to keep the reverberation time as short as possible at 125 Hz if it is to be used for people with a hearing impairment.
Otherwise it is not allowed to be increased more than 0,1 seconds.
At low frequencies we have a lot of standing waves giving longer reverberation and higher levels.
That gives masking effect both in time and level and even if it not directly affects the possibly to understand, it affects the concentration and increase tiredness.
There exist several ways to absorb low frequencies and it would be much to win to find easy effective ways to do so in order to get a higher output from the learning process in schools.
Click here for the full list of Abstracts from EIAS 2011 and the other workshops
