We live and work in buildings; structures comprised of four walls, a roof and a floor. However, it is the technologies and products obscured within these walls that dictate whether a building is comfortable or not to be in for long periods of time.
Given the fact that pupils spend 190 days per year at school, good acoustic performance in educational buildings is crucial for effective learning. The schools, colleges and universities throughout the UK are responsible for the creation and nurturing of future medical professionals, entrepreneurs, teachers and artists – it is vital that pupils are able to listen clearly to their teacher’s communications in order to foster the learning process.
It has been proven by many studies that poor acoustic performance within a classroom severely hinders learning and teaching. Let’s take a closer look at the subject of sound:
What is sound?
Okay, we all know what a sound is… but it is important that we understand how it works when discussing acoustic insulation. Sound is a form of energy created when air is disturbed in some way causing changes in air pressure that radiate from the source of the sound in waves. Sound can be airborne; typically that of a human voice.
Sound waves vibrate at different rates or frequencies as they move through the air and are measured in cycles per second or Hertz; the faster a sound wave passes a given point, the shorter the wavelength and in turn the higher the frequency. Vibrations in the air caused by the sound determine how loud it is; the stronger the vibrations the greater the ‘amplitude’. The length or duration of a sound i.e. it’s reverberation time or echo, is determined by the extent to which the energy is expended on contact with surfaces within a room.
How is sound measured?
Sound is measured in decibels using logarithmic scales; the human ear is incredibly sensitive and the scale needs to reflect this. The table below shows the increase in sound intensity in relation to decibel levels.
How are we affected by sound and levels of noise?
The human ear can hear sounds across the frequency range 20 to 20,000Hz; however it is most sensitive in the range 100 to 5000 Hz. There is a great deal of variation in the hearing abilities of individuals and the awareness of sounds can depend not only on physical but also psychological factors. Noise can be described as unwanted sound; however the level at which noise is tolerable is subjective – a specific noise that one person finds upsetting may go unnoticed by another.
Background noise in buildings normally arises from sources like external traffic or equipment within the building. Machines like air conditioning units or fans can operate at moderate levels that make noise that is unobtrusive and is only noticed when turned off. This sort of noise is often unnoticed as it is steady and conveys little information about events around it. As an unintended consequence of normal activities, background noise can be beneficial in masking more sounds from an adjacent room without being loud enough to be noticed in their own right.
How does noise affect educational environments?
The three main sources of noise which affect classrooms are airborne sound sources, implact sound sources and general reverberation noise. Reverberation is a common problem and has a potentially significant impact on the classroom environment. Challenges such as background noise and group work where discussions and debates are encouraged mean that if a classroom isn’t properly soundproofed, noise levels will crescendo to uncomfortable levels and as a result will hinder any learning ability.
It is important to realise that there are a variety of educational methods and styles presented in the modern day classroom, each with their own noise issues. The more traditional teacher/lecture based classroom is where a teacher is located at the front of a classroom and leads any communication or discussion. This teaching function potentially suffers greatly from reverberation noise levels as pupils who sit toward the back of the classroom will suffer from reflected noise levels, where the teacher’s voice is at the weakest point due to reflected sound waves.
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A more modern approach to teaching focuses on a more interactive based learning where students are encouraged to work in pairs or groups to facilitate learning processes. This means within a classroom, reverberation and ambient noise levels will increase dramatically, and if a room is untreated the noise levels will hamper concentration levels and learning ability.
Airborne sound sources affect educational environments where sound travels from different rooms within a building, particularly through separating walls or floors. This is particularly relevant where a classroom is situated next to a music room or a library, which is next to a busy corridor. Airborne noise levels are determined by the use of the area, as some areas will generate more noise than others meaning these will need to be looked at in more detail.
Impact sound sources are sudden noises that come through a floor construction like footsteps. It is imperative that impact noise is taken into account to ensure pupils movements in the classroom above are not heard below.
UK Building Regulations and the guidance in Building Bulletin 93, stipulate that these noises are controlled and that every room or space within an education building is designed in such a way as to achieve a certain level of acoustic performance.
Sound insulation in buildings
The movement of sound around a building is a complex process that can be affected by a whole host of factors both within and around a site. There are also various ways of measuring and expressing levels and performance.
Problems can occur with the level of acoustic control in a building and this may be because:
- The building design does not lend itself to acoustic control
- The specification of individual components is incorrect
- The interaction between individual elements is not given full consideration
- One of the parties or suppliers involved has used inappropriate information to gain a commercial advantage
The classrooms in which children are taught have more demands upon them than ever before. They are places to learn, to play and to be inspired. But if the students cannot hear their teacher, or are distracted and stressed by unwanted noise, then their learning experience will suffer. It doesn’t need to be that way.
A number of regulations and guidance apply to acoustic standards, and projects to refurbish classrooms and teaching spaces that provide for children with special educational needs should take these into account. Within the UK the acoustic standards are set by Building Bulletin 93 (BB93) and similar standards are in development in the Republic of Ireland.
Improving classroom acoustics need not be challenging or expensive. If you are currently working on an educational project, place yourself in the position of a pupil sitting within the classroom you are building for a moment in your mind… can you concentrate?