Acoustics in Schools BB93

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	Recent studies have shown that many classrooms have poor acoustics. As a result, children with normal hearing are often unable to make out what is being said in class. While adults will guess at missing words, children find it much harder to fill in the gaps and their educational development can suffer. Download PDF Brochure
Building Bulletin 93	Before 2003, Part E of the Building Regulations did not apply to schools until recently. It also requires sound absorption for entrance halls, corridors or hallways in multiple dwellings such as flats. All school buildings are now subject to detailed design checks and on-site inspections by building control officers. Section 1 of Building Bulletin 93 describes the 'Specification of acoustic performance'. This section gives the performance targets for compliance with the Requirement from Part E of the Building Regulations 2000 (as amended): “Each room or other space in a school building shall have the acoustic conditions and the insulation against disturbance by noise appropriate to its normal use.” Building Bulletin 93 aims to : Provide a regulatory framework for the acoustic design of schools in support of the Building Regulations. Give supporting advice and recommendations for planning and design of schools. Provide a comprehensive guide for architects, building control officers, building services engineers, clients and others involved in the design of new school buildings.
Why are Some Rooms Acoustically Poor?	There are three main reasons why rooms may be acoustically bad for speech: They may be too reverberant for the speech sounds produced in them They may be noisy because of weak resistance they offer to the penetration of noise from outside or from nearby rooms. They may be shaped so that the speakers are more or less screened from their audience or part of it.
Effect of Reverberation on Speech	Part of the sound from a teacher passes directly to the ears of his/her pupils. Another part travels to the rooms surfaces and is reflected, eventually reaching the pupils ears from many directions at close intervals: this is called reverberant sound. If there is too much reverberant sound, the pupil is still receiving the reflected sounds of previous syllables when trying to cope with the direct sound of later syllables. The two then interfere, and speech is difficult to understand. The amount of reverberation is usually expressed as the reverberation time, which is the time taken for the sound to die away after its source has stopped. It may vary from half a second in an ordinary living room to 8 seconds or more in a large assembly hall or gymnasium.
		A classroom or teaching space with a long reverberation time of several seconds will cause syllables to be prolonged so that they overlap and hence degrade speech intelligibility. Long reverberation times occur in large rooms with hard wall, floors and ceiling surfaces. Adding acoustic absorption panels or tiles will reduce the reverberation time and will improve speech intelligibility.
	Building Bulletin 93 specifies the reverberation times required for various teaching spaces ranging from classrooms to assembly halls.
Amount of Acoustic Absorption Required	In classrooms and other rooms for speech, large amounts of fixed acoustic absorption are often required particularly where rooms have high volumes, as often occurs in older buildings. It is advisable to contact the technical department of Soundsorba Ltd so that the correct amount of sound absorption can be calculated for the space in question.
Corridors, Entrance Halls and Stairwells	The Building Regulations Approved Document E also contains guidance on the addition of sound absorption to common areas in buildings containing multiple dwellings such as flats. This gives two methods for the application of sound absorbers: Method 1. A Class C performance absorber for entrance halls, corridors or hallways to cover an area equal to or greater than the floor area to be applied ,generally to the ceiling. The ECHOSORBA stick-on acoustic panel meets this requirement. For stairwells or a stair enclosure, the requirement is to cover an area of at least 50% of the ceiling with a Class C absorber, (ECHOSORBA acoustic panel is a Class C absorber in 30mm thickness) of the combined area of the stair treads, the upper surface of the landings (excluding ground floor ) and the top floor ceiling area. Method 2. This needs detailed acoustic calculations to assess the amount of absorption required. Please contact Soundsorba Ltd for technical assistance on this method.
Solutions to Acoustic Problems in Schools to meet BB93		Assembly Halls These spaces are increasingly used in schools for a wide range of activities and not confined to just assembly. Typical solution is to line high level wall surfaces with WALLSORBA acoustic panels and if necessary, add some ECHOSORBA acoustic panels on part of the ceiling.
	Reverberation time of 0.8 to 1.2 seconds is required for assembly halls.
		Sports Halls Sports halls are designed with robust and impact resistant constructions as these spaces will need to suffer years of long term use. All these hard surfaces combine to produce an ‘echo chamber’ in the building. This makes conveying instructions to pupils very difficult as speech is unintelligible. Solution to this problem is line the walls at high level, with WALLSORBA acoustic wall panels. These are robust as they will withstand impact from indoor footballs etc.
	Reverberation time of less than 1.5 seconds is required for sports halls.
		Classrooms These are the most common teaching spaces in any school and hence the most important. They tend to cater mainly for around 20 to 30 pupils and one teacher. The intelligibility of the spoken word is paramount. Acoustic solutions to these rooms can be the installation of WALLSORBA acoustic panels in a horizontal band at high level on the walls and/or ECHOSORBA acoustic panels on the ceiling or FOAMSORBA stick on acoustic tiles on the ceiling.
	Reverberation time of less than 0.6 or 0.8 seconds is required for classrooms
		Music Rooms Music rooms present the greatest difficulties when is comes to dealing with acoustics in schools. This is because they generate the highest level of sound and are the most sensitive to noise intrusion to and from others areas. Normal acoustic treatment is to install WALLSORBA acoustic panels on the walls and FOAMSORBA ICE acoustic tiles on the ceilings/walls. If extra low frequency absorption is required then ECHOSORBA panels can be installed in selected areas. DOORSORBA acoustic door sets can be used to deal with sound transmission problems.
	Reverberation time of less than 1.0 second is required for music classrooms and less than 0.8 seconds for small practice /group rooms.
		Dining Rooms These rooms are designed to take a lot of punishment and all the surfaces are hard and cleanable.It is important in these spaces that acoustic absorbers are kept at high level, well away from reach by hands etc. ECHOSORBA acoustic panels and WALLSORBA acoustic wall panels are ideal for these areas. In some situations, BAFFLESORBA hanging absorbers will be suitable.
	Reverberation time of less than 1.0 second is required for dining rooms.
		Music Recording Rooms BB93 requires sound insulation through wall structure of music practice rooms. All spaces used by students except music rooms require a minimum sound insulation value of Rw 30dB for doorsets.DOORSORBA acoustic door sets are manufactured and offered in two acoustic ratings. One is 35dB and the second is 44dB and therefore both meet the sound insulation performance of BB93 standard.
	Reverberation time of less than 1.0 second is required for dining rooms.
		Swimming Pools Pools are very reflective to sound due to tiled walls and floor surfaces. One of the largest sound reflective areas in the swimming pool is the water itself which reflects 99% of the sound which hits it. Practical solutions to soak up the reverberant noise levels are to apply BAFFLESORBA hanging absorbers or FOAMSORBA acoustic tiles with large shadow gaps between the tiles.
	Reverberation time of less than 2 seconds is required for swimming pools.
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