The Sound Environment Center at Lund University:
Proposal for an Inventory of Acoustic Properties in the
Lecture Halls of Lund University
Introduction
The Sound Environment Center at Lund university arranged a meeting at Biskopshuset the
29/11 2012 regarding possibilities to optimize acoustics at campus in favour of better
cognitive performance of students. Approximately thirty stakeholders and researchers where
present at the meeting including a brief visit from the vice chancellor. Consensus was noted
around the need to initially start investigating the current situation at the university to be able
to be able to get a picture of the present state and suggest a plan for improvement work.
Another meeting was subsequently arranged at the department for Technical Acoustics at
LTH assembling representatives from the Sound Environment Center, technical acoustics,
logopedics, audiology and cognitive science to draw plans for a larger research concept
putting focus on the demands in higher education of cognitive functionality, and on how this
is affected by properties of sound and light in educational premises.
The overall research concept includes observation areas along the whole communication
process ranging from source to receiver involving a number of different academic
disciplines; from the source to the receiver: audiology, logopedics (source), room acoustics,
architecture (channel) and cognitive science, environmental psychology (receiver).
The first and second part build on knowledge and competences within the center attained in
the work of Jonas Brunskog (acoustics DTU) and Viveka Lyberg Åhlander (logopedics, LU)
in their interdisciplinary collaborations within the AFA financed ”Speakers Comfort project” Talarkomfort och röstohälsa i skolsalar. This is a large and successful project studying
effects of room acoustic properties on voice production and voice health. Factors that in turn
strongly affects speech intelligibility and transmission of information. The success of this
project has emanated in another, by AFA fully financed project investigating development of
voice disorders in association with acoustic properties. ”Damage and healing processes for
voice health - High speed camera and biomechanical models”. As for the third area
(reciever), resources at the humanistic laboratory and environmental psychology department
will be involved.
Applications for external funding based on this larger interdisciplinary research theme are
currently being planned once investigations of the current state of acoustics at LU campus
have been made.
The first step however, is to understand, explain and initiate changes for the better by initially
making an inventory of acoustic properties. In order to realize this, resources are applied for
in the following proposal.
Background.
In lecture rooms, the primary methods of communication are speech and listening. There are
different factors affecting the effectiveness of the learning conditions, like speech
intelligibility in rooms, reverberation times and background noise levels. Non optimal
acoustical conditions directly affect the student speech perception and also the instructors,
thus, reduces student learning efficiency. If properties of sound are not satisfactory,
disturbances and problems of understanding and memorizing will be experienced by not
only the average student, but evermore so by all the students with any kind of impairments,
be it hearing, sight or language difficulties. In the references [29]-[31] include design guides
to achieve better acoustic environment for students, to learn in.
While the teaching environment is important for students, it is equally important to teachers.
Teachers suffer from health problems related to their voice. These problems are strongly
related to the working environment of teachers including the acoustics of the classrooms, the
behavior of students and overall working conditions. For the teacher, in the long run, this
voice load due to speaking in the classroom can result in voice disorders such as
hoarseness, voice fatigue and can even force teachers to retire early from their profession.
We have decided to focus our primary and initial efforts on a ‘’physical’’ approach. How to
improve the acoustics properties of lecture hall/classrooms based on measurements? We
will not only work with reverberation time or/and speech quality as often mentioned (see
related works), but we will investigate known acoustical parameters to find a relation
between good cognitive perception and these parameters.
Our contribution will be, in more details
•
•
An investigation into the current state of the acoustic performance of a subset of the
lecture halls at Lund University will be performed. The investigation shall be made
using state-of–the art measurement equipment and also include long-term
measurements of typical lecture halls.
Amplified and non-amplified sound system should be measured, including speech
processing solutions to improve voice support (developing audio algorithms).
.
The measured and investigated parameters should be:
• Reverberation time (EDT, T20,T30) according to ISO 3382-1
• Speech clarity (C50) according to ISO 3382-1
• Sound strength (G) according to ISO 3382-1
• Speech intelligibility STI, RASTI according to IEC 60268
• Sound reduction
• Interaural cross correlation IACC
• New acoustic measures, such as ”room gain” and ”voice support”
• In parallel with the acoustic measurements surveys and questionnaires will provide
information on how subjective parameters of the present acoustics are experienced
by the students and lecturers. The results from these will be compared to the
measurements of the investigated parameters; correlates identified as well eventual
implications of these.
The main outcomes of this project will be to be able to support and guide Akademiska Hus
and Lund university in their renovation projects and to provide guidelines for future
educational premises.
Related previous studies
Studies brought forth by HRF (The national organization for hearing impaired, Sweden) have
shown that not only hearing impaired, but also normal hearing students tends to experience
severe loss of learning effectiveness due to bad acoustic conditions in many Swedish high
school and university environments [14-17].
The adverse effect from poor acoustic performance is being highlighted more and more in
the scientific literature. These effects range from degraded perceptibility and mild discomfort
to stress and even health related problems. Indeed, for dyslexic individuals it has been
shown that the sound quality has a deep impact on the development of the disability [18].
Most studies performed have been conducted on pre-school children, but also young adults
and the society as a whole are the subjects in a number of studies [1-13]. The utilization of
lecture halls is cost-effective in transmitting knowledge to large audience, but this
effectiveness is degraded if the acoustic performance is poor and if the audio visual aids are
not carefully chosen.
Room parameters are often divided into objective and subjective where objective are
measurable quantities used for characterizing the quality of the sound environment and the
subjective refers to the perception of sound and how it affects the students as well as
teachers in terms of e.g. performance, ability to concentrate, correct perceiving of
information and well-being.
One further aspect and motive for the design of the sound environment of lecture rooms is
the speaker comfort. It has been shown in pilot studies that some parameters, such as
reverberation time and “room gain”, are correlated to a perceived good environment as well
as sound power produced by the speaker [19-21].
A central aim of room acoustic analysis and psychoacoustics is to investigate a number of
objective measures, identify the most relevant of these measures and relate them to
investigated subjective parameters. These relations should be evaluated by an extensive
correlation analysis which in turn can provide guidance to future design of healthy learning
environments. Typically, in Swedish learning environments as well as other workplaces, the
regulations for lecturing rooms are stated according to Swedish standard SS 25268:2007
[22]. This comprises values for reverberation time, noise from installations, weighted sound
reduction index and weighted step sound index. However, it has been shown that other
objective measures can be of more relevance in order to characterize a good sound
environment, measures such as speech clarity, early decay time, sound strength etc. [2328].
Current status at Lund University
There are several lecture halls at Lund University, some of these have been designed quite
recently while others were constructed many years ago. As the use of audio-visual
equipment as well as the use of enabling techniques for disabled students is continuingly
increasing. Lecture halls, which have not been explicitly designed for the use of such
equipment, are being fitted with an assortment of audio-visual fixtures. Although this is
meant to facilitate communication, it can easily lead to far less-than-optimal acoustic
performances. As the acoustic performance of the environment profoundly impacts the
outcome of the learning process the conclusion must be that it is of primary importance to
assess the current state of the situation with respect to the acoustic performance of lecture
halls at Lund University.
There are about 60 Lecture halls at Lund University with a capacity over 60 students. Of
these about half have been fitted with audio-visual equipment, therefore the acoustic
implications of this have to be taken into account.
To provide sound environments better suited to learning situations is not only a matter of
comfort, but of democracy, to give everybody equal access to lectures and learning, and
therefore a central part of the ambitions of Lund University.
All in all can be noted the need for a revision of the acoustic properties at Lund University,
and for the making of an inventory and proposing of plans for improvements, to be able to
come to terms with older halls, as well as avoiding problems in the new halls prospected
today.
Lund University should have exceptionally good lecture halls in terms of acoustics.
lecture halls are designed to meet requirements and measures according to
knowledge it can be used in order to broadcast the progressive development of
University, being the university considering both the listeners and the teachers
designing rooms.
If the
latest
Lund
when
Time schedule and research “milestones”
Milestone
no
1
Activity
2
Literature survey
3
6
Plan for subjective
and objective
measurements
Measurements in
lectures halls
Extraction of
measurements and
first results
Correlation
7
Correlation cont.
8
Dissemination
(continously),
4
5
9
Kick off
Delivery
date
October
2014
January
2015
February
2015
Comments
September
2015
September
2016
peer review
article no one
peer review
article no two
February
2017
peer review
article no three
September
2017
January
2018
peer review
article no four
Peer review
article no five
End of 2018
Project leadership and members
This project is initiated by Ljudmiljöcentrum at Lund University. The acoustic investigation
will be headed by Associate Prof. Delphine Bard from Technical Acoustics together will
Anders Sjöström from Technical Acoustics. Some measurements will be conducted by
master students connected to Technical Acoustics and The Sound Environment Center.
Scientific consultancy will be provided by ass. prof. Jonas Brunskog, DTU and Dr. Viveka
Lyberg Åhlander at logopedics.
External acoustic consultants may also be called in according to needs. The project plans
have been met with interest by a number of the larger concultancy companies and
institutions in Sweden.
A larger group of researchers are expected to join at a later stage. Amongst people
contacted who has shown interest may be mentioned Marianne Gullberg, Professor
Psycholinguistics and Director of the Humanities Lab, Jonas Brännström, DMSc., Associate
professor, Department of Logopedics, Phoniatrics, and Audiology, Clinical Sciences
Lund.audiology & Tobjörn Laike, professor, Environmental psychology
Budget
The project will run for 18 months.
Costs without OH
OH 100%
OH 40%
DB (Salary@100%)
1171458
2342916
1640041,2
A S (Salary@50 %)
455265
910530
637371
3253446
2277412,2
Odeon software
70000
70000
70000
Laptop computer
25000
25000
25000
3348446
2372412,2
Total budget
References
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f
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Lund 2007.
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Lund, 2014-06-09
Coordinator, Frans Mossberg
Project Leader, Delphine Bard