Successful architecture means that rooms for speech must also be designed to facilitate clear communication with consideration to the function and layout of the space. This implies that designers, architects and acoustic consultants should actively collaborate.
We know that the most successful projects will be ergonomically designed to consist of both positive aesthetic and acoustical qualities. The result of ineffective or non-existent collaboration will lead to issues for end-users such as inefficient and costly redesign practices. Architects and designers must consider beyond the aesthetics, and acoustic consultants must consider more than the auditory environment.
The significance of acoustic comfort has become well known throughout numerous studies, research and many individual personal experiences. I’m sure that most can all think of a time when we have been enveloped within an acoustically challenging environment! It is often the case that good acoustical environments go unnoticed, with a poor acoustic environment causing noticeable discomfort.
Acoustics in Education
School acoustic design for educational buildings is a critical aspect of modern learning environments. Rooms must be designed to facilitate clear communication between teachers and students. Without good acoustic design, the learning space may not be suitable for its intended use.
School children spend an average of four to five hours per day in classrooms . Research suggests that children are more susceptible to poor acoustics than adults [2, 3]. They are neurologically undeveloped and lack experience to predict from context, especially younger students who are only starting to grasp the basics of comprehension . This means that when designing for schools, extra attention must be paid to the acoustics. It is important to remember that the adults who design the space must factor in that the children who will later occupy the space will have a differing auditory experience.
Repercussions for children in poor acoustic environments include; negatively affected concentration, language development, behaviour, attention and academic performance [5, 6]. Another paper has linked poor acoustics to lower skill levels in students, which can cause significant economic loss to an individual over a lifetime .
What about Teachers?
Studies also show that poor classroom acoustics can negatively impact a teacher's work environment. One study shows that classrooms with poor acoustics can affect a teacher's heart rate and stress levels . Another study found that 71% of surveyed teachers have reported that noise generated within a classroom is a problem . Voice care guidelines also state that teachers are at risk when using their voices in environments that are not conducive to safe voice production like rooms with poor acoustics .
Hearing Impaired and ESL Students
Poor classroom acoustics can have an increased negative impact on children with hearing impairments and English as a second language (ESL). With a growing number of these students, inclusivity demands that optimal acoustics are provided. It has been reported that these groups can make up 25-30% of students in primary school classes . The Royal Institute for Deaf and Blind Children states that 2 in every 1000 children have been identified with hearing loss . Children with learning disabilities and attention problems, who make up to 20% of government students  will also benefit from optimised acoustics .
Open Plan Classrooms
With modern school designs incorporating elements of open plan design, achieving optimised acoustics has become more challenging to implement. This is because the acoustic environment becomes significantly more complex.
Research shows that open plan classrooms can benefit both teachers and students. We are also aware that without suitable acoustic advice, these spaces can easily become poor acoustic environments and will no longer be fit for purpose. One study shows that intrusive noise levels within studied open plan classrooms were not within the recommended levels according to standard . Another study shows the challenges of refurbishing teaching spaces into innovative learning environments (ILE) with an open plan layout can create a poor acoustic environment. It was reported that “the students were distracted and seemingly off task or having difficulty concentrating” .
Common activities in these spaces consist of various kinds of group work. The main issue here is noise intrusion from the adjacent learning activities. This creates a build up of noise (in particular low frequencies) that in turn cause the occupants to continually increase their voices, increasing the overall sound levels in the room. This is known as the "Lombard effect". Essentially, this leads to a poor acoustic environment.
Classroom Acoustic Standards
According to AS/NZS 2107:2016 certain teaching spaces, including those intended for students with listening difficulties and students with English as a second language, should have reverberation times at the lower end of the range . The DETE recommends that teaching spaces shall have reverberation times lower than the nominated minimum level . The EPA recommends that children should be exposed to quiet learning environments .
Essentially, this means that shorter reverberation times with acoustically treated surfaces are ideal. Hard surfaces like plasterboard, concrete and solid floors should be avoided, as these will create longer reverberation times. Long reverberation times cause syllables to be prolonged and in turn will reduce the quality of the acoustic environment. Long reverberation times are also responsible for exacerbating the Lombard effect.
Solutions with Decorative Acoustic Panels
Shorter reverberation times should be implemented to reduce noise from compounding background activity and disturbing the other class groups. In most cases, good classroom acoustics can be achieved by designing to the recommended reverberation times and noise levels set out in AS/NZS 2107:2016. This means that utilising decorative acoustic panels in the design stages in collaboration with your acoustic consultant.
Acoustic absorption should be evenly distributed throughout the space, although in many cases you will find that the first place utilised is the ceiling. It is also important to understand the way that reverberation time is calculated assumes that absorption is evenly distributed throughout the space.
The diffusive properties of room finishes and contents can also be strategized to influence the quality of room acoustics. For example, a bookcase on a rear wall can be used to scatter sound within a space and break up long delayed echoes. This is especially important in rooms with a rear wall distance greater than 8.5 metres.
Reflection is also important, with short delays under 50 milliseconds being beneficial to speech intelligibility. It is when strong reflections after 50 milliseconds occur that a degradation of speech intelligibility will occur. This is especially beneficial in traditional teaching spaces and lecture halls, however needs to be more strategic in open plan learning environments.
Resonant absorbers such as fire-rated timber acoustic panels can be especially effective as they can be used to provide a healthy amount of absorption across the frequency spectrum. This means that they do not promote excessive high frequency absorption, which can be especially important for rooms with lots of carpet installed.
They can also be tuned to provide effective low frequency absorption. This is important for hearing impaired students who make use of low frequencies below 500Hz to obtain information from speech .
What about Multi-purpose Halls?
In some cases, single flexible school hall acoustics become relevant. This is where a space could be used for a variety of applications all requiring differing acoustic requirements. For instance, a multi-purpose hall may be required to be used as an assembly hall, a music performance venue or a sports court.
This means that optimising acoustics for all purposes becomes more challenging as each function requires differing acoustic requirements. An example is that music performance acoustics would benefit from a longer reverberation time than a hall for speech. In general though, these spaces require strong acoustic panel treatments for long delayed echoes and flutter echoes with an even distribution of acoustic treatment throughout the design, not just on the ceiling. (See here for information and an example of flutter echo).
Ultimately, the main function of the space should take precedence here or other strategies such as operable acoustic treatments could be used.
Requirements other than reverberation control are important factors when acoustically designing in education. Comprehensive analysis and collaboration should be conducted with your acoustic consultant on any education project.
You can find qualified acoustic consultants here; https://aaac.org.au/member-firms
About the Author
Michael Phillips is an acoustic engineer who specialises in engineering acoustic treatments for both aesthetic and acoustic design requirements.
Creator of bespoke treatments including; diffusion and absorption, wall and ceiling systems, curved beams and panels.
For more information on acoustic solutions, email Michael at [email protected] or phone 61+ 02 6333 8014.
1. Association of Australian Acoustical Consultants Guideline for Educational Facilities Acoustics, 2010, Association of Australian Acoustical Consultants (AAAC), Available at: www.aaac.org.au.
2. Lucy C. Erickson and Rochelle S. Newman ‘Influences of background noise on infants and children’, Curr Dir Psychol Sci. 2017; 26(5): 451–457. Published online 2017 Oct 10
3. Kiri Mealings ‘Classroom acoustic conditions: Understanding what is suitable through a review of national and international standards, recommendations, and live classroom measurements’ Department of Linguistics, Macquarie University, Sydney, Australia National Acoustic Laboratories, Sydney, Australia, 2016
4. Valentine, J., Wilson, O., Halstead, M., McGunnigle, K., Dodd, G., Hellier, A., Wood, J., & Simpson, R.. ‘Classroom Acoustics: A New Zealand Perspective. Oticon Foundation in New Zealand’, 2002
5. America Speech Language Association https://www.asha.org/public/hearing/Classroom-Acoustics/ Accessed January 2020
6. Joseph J. Smaldino, Carl C. Crandell ‘Classroom Acoustics for Children With Normal Hearing and With Hearing Impairment’ University of Florida, Gainesville University of Northern Iowa, Cedar Falls, 2000
7. Deb James (1), Matthew Stead (1), David Clifton-Brown (2) and David Scott (2)
'A cost benefit analysis of providing a ‘sound’ environment in educational facilities’
(1) Resonate Acoustics, 97 Carrington Street Adelaide SA 5000, Australia
(2) Donald Cant Watts Corke, Level 5, 115 Grenfell Street, Adelaide SA 5000, Australia, 2012
8. Tiesler, G., Machner, R., & Brokmann, H.: “Classroom Acoustics and Impact on Health and Social Behaviour” in Energy Procedia 78, 2015, Elsevier Ltd. pp. 3108-3113
9. Joanne Valentine – Marshall Day Acoustics Oriole Wilson – National Audiology Centre Other Authors: Acoustics Miklin Halstead1 , George Dodd1 , Ken McGunnigle2 , AnneHellier3 , John Wood3 ‘Classroom Acoustics - A New Zealand Perspective’ Research Centre, University of Auckland1 , Prendos NZ Ltd2 , Specialist Education Services, Ministry of Education3 .
10. Victoria State Government Voice Care Guidelines, Page 8, last updated 9th August 2018
11. ANSI S12.60-2010 American National Standard Acoustical Performance Criteria, Design
Requirements, and Guidelines for Schools, Accessed January 2020
12. Royal Institute for Deaf and Blind Children https://www.ridbc.org.au/fact-list Accessed January 2020
13. NATASHA BITA ‘One in five students has a disability: confidential data’ 12:00AM MARCH 12, 2016 https://www.theaustralian.com.au/nation/education/one-in-five-students-has-a-disability-confidential-data/news-story/a3b1360c2185890344aa79e7f9097c73
14. Australia/New Zealand Standard, 2016, AS/NZS2107:2016, Acoustics - Recommended design sound levels and reverberation times for building interiors, Australia/New Zealand Standard.
15. Amanda Robinson (1) and Anne Bellert (2) ‘Co-teaching in (refurbished) flexible learning spaces: Promoting quality acoustics for learning and collaboration’
(1) Co CEO, Marshall Day Acoustics, Melbourne, Australia
(2) Senior Lecturer, School of Education, Southern Cross University. NSW, Australia
16. Design Standards for DETE Facilities, 4.9.3 Acoustic Absorption, page 110
17. Kiri Trengove MEALINGS1 ; Jorg M. BUCHHOLZ2 ; Katherine DEMUTH3 ; Harvey DILLON4 1,2,3 ‘An investigation into the acoustics of an open plan compared to enclosed Kindergarten classroom’ Macquarie University, Australia 2,4 National Acoustics Laboratories, Australia
18. Noise and its Effects on Children
19. Building Bulletin 93 - Acoustic Design of Schools, A Design Guide, Section 6, Page 77