THERE CAN BE FEW BUILDING TYPES where acoustic design plays such a key role in the success of the people who use the building. A review of 30 years’ worth of international research (Shield & Dockrell, 2003) highlighted that acoustics in the classroom can impact on student memory retention and concentration levels. The research shows that the acoustic environment can alter performance in mathematics, problem solving, reading ability, language skills, and impact on literacy levels. It should be noted that these studies are on children classified as having standard hearing ability. The need for social inclusion of children with hearing impairments and special educational needs only increases potential for poor acoustic design to adversely affect performance.
Research (Canning & James, 2012) has also shown that applying standards normally associated with special teaching facilities for hearing impaired children can have a significant effect on educational attainment, behavior, and even teacher and student comfort. Therefore it is worth considering the application of higher standards rather than aiming to achieve a basic level of performance.
The following section provides general good practices for the design of school buildings looking at the control of reverberation, noise disturbance, and speech intelligibility.
7.2.1 Performance specifications
The aim of any acoustic design for an educational building is to minimize the likelihood of disruption to the students, make it as easy as possible for the students to hear the teacher and each other, and as easy as possible for the teacher to hear the students.
To achieve this, the acoustic design of any educational building will look at three key factors:
controlling noise break-in from external sources (location, orientation, façade, roof, and ventilation design)
controlling the transfer of sound within the school (layout, partition, detailing design, HVAC design)
controlling the reverberation time within a school (room size, room shape, room finishes)
7.2.2 Signal to Noise Ratio (SNR)
Table 7.1 details accepted good guidelines with regards to signal to noise ratios in classrooms.
7.2.3 External noise limits
Controlling noise within schools grounds is important; these areas can be used for teaching activities. Table 7.2 outlines suitable external noise limits around a school.
Where measurements indicate that noise levels on a proposed school site are below LAeq 45 dB, then this can be seen as a positive indication that no mitigation work would be required to protect either the external or internal teaching areas. Where noise levels exceed the values expressed in Table 7.2, external mitigation work may be necessary.
Table 7.1 Good practice guidelines on signal to noise ratios for teaching rooms (adapted from EFA, 2012)
Standard | Description | Signal to Noise |
Minimum | For students without hearing impairment or Special Education Needs (SEN) | >10 dB |
Basic | For all students, including hearing impaired and SEN | >15 dB |
Enhanced | For all students including hearing impaired and SEN | >20 dB 125 Hz–750 Hz >15 dB 750 Hz–4 kHz |
Table 7.2 Permissible upper noise limits for external space around a school (adapted from DoE, 2004)
Location | Permissible upper limit LAeq (dB) |
Noise level at proposed school façade | 60 dB |
Outdoor area used for informal teaching | 60 dB |
Outdoor recreation areas | 60 dB |
Playing fields/sports fields (unoccupied) | 55 dB |
Outdoor formal teaching | 50 dB |
7.2.4 Doors between teaching spaces and circulation areas
For schools it is accepted that the level of sound insulation for corridor walls separating rooms from circulation spaces which have doors or glazing in them would not be testable on site. Therefore a performance criterion based on laboratory performance should be set. This means that laboratory test data can be used as evidence that a partition specification is suitable for use.
For all rooms to circulation spaces except music rooms, a minimum standard would be STC/Rw 40 dB for the wall and STC/Rw 30 dB for the door set.
For music rooms to circulation spaces, a minimum standard would be STC/Rw 45 dB for the wall and STC/Rw 35 dB for the door.
7.2.5 Internal openings
Table 7.3 provides guidance on suitable performance levels for doors, roller doors to server hatches, demountable partitions, and glazed screens for vision panels.
7.3.1 Controlling external noise
When considering the location and positioning of a school, consideration must be given to providing quiet external areas as well as ensuring quiet internal areas.
Minimum distances between educational buildings and transportation noise sources: It is considered best practice to locate schools 328 ft (100 m) from any busy road or railway line; however, it is anticipated that achieving these sorts of distances in urban locations will be difficult. Standoff distance between schools and busy roads of 65 ft (20 m), and 98 ft (30 m) between schools and railway lines, should be seen as an absolute minimum. Locating the building closer increases the likelihood for vibration and reradiated sound becoming a problem. It should be noted that at these minimum distances noise from a road or railway is likely to still be a significant issue and will need to be controlled.
Table 7.3 Suggested performance requirements for openings in internal walls
Opening type | Suggested specification | Expected Performance rating STC/Rw dB | Suitable location |
Serving hatch | 100 mm galvanized steel slats minimum surface density of 50 kg/m2 | 25 | • Serving hatch between kitchen and dining halls |
Particle board clad in vinyl/fabric/veneer, etc. either side of steel frame with mineral fiber insulation infill. Nominal 64 kg/m2 hanging weight | 52 | • Drama studio to other teaching space • Between sports halls • Between multipurpose halls/dining halls | |
Standard door | Timber/metal door (light 44 mm @ 27 kg/m2) | 30 | • Standard teaching spaces to corridor • Ancillary rooms to corridor |
Enhanced door | Timber/metal door (heavy 54 mm @ 29 kg/m2) | 35 | • Music rooms to corridor • Control rooms to corridor • Drama rooms to corridor • Multipurpose halls to corridor • Rooms for children with special hearing or communication needs to corridor` • Interconnecting door standard teaching spaces |
Optimum door | Back-to-back timber/metal door (heavy 54 mm @ 29 kg/m2) | 40 | • Interconnecting music rooms |
Unrated vision panel | Single layer of glass in sliding frame | n/a | • Where visual and verbal communication is required, e.g. reception desk to waiting room |
Standard vision panel | 10mm float glass/12mm cavity/6.4 mm laminate glass | 40 | • Glazing set into a corridor wall or door frame between a standard teaching space and circulation space |
Enhanced vision panel | 6mm float glass/100 mm cavity/4 mm float glass | 45 | • Where visual communication is required between teaching spaces e.g. teaching space to multipurpose hall |
Optimum vision panel | 10 mm float glass/200 mm cavity/6 mm laminated glass (absorptive lining to window reveal between panes of glass) | 49 | • Between music rooms/recording studio and control rooms |
Through wall ventilator | 2 m2 open area vent with 50 percent open, 50 percent open-cell foam, minimum length 1.1 m | Dne,w 39dB | • Cross-ventilation via corridor walls |