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Classroom Acoustics

Classroom Acoustics - recommended standards
Source: The British Association of Teachers of the Deaf

Unoccupied Ambient Noise Level	should not exceed	35 dB(A)
Reverberation Time	should not exceed	0.4 second across the frequency range 125Hz to 400Hz
Signal To Noise Ratio	should exceed	20 dB across the frequency range 125Hz to 750Hz 15 dB across the frequency range 75Hz to 400Hz

Early diagnosis of hearing loss together with good pre-school guidance, consistent appropriate hearing L aid filling and cochlear implants are making it possible for severely and profoundly deaf pupils to be educated in mainstream classes. The government policy of inclusion also encourages this situation.

It is therefore important to have realistic targets for acoustic conditions in schools in order to influence either existing provision or new building regulations. Good acoustic conditions benefit both hearing and deaf pupils. However, classroom acoustics is only one of many factors which will support or inhibit the successful inclusion of severely and profoundly deaf pupils.

Recommended standards need to be used sensitively and put in the context of other strategies used by pupils and staff. They would be one factor in the learning environment and the impact on individuals will be variable.

Background Noise Levels (BNL) and Reverberation Times (RT) can be improved by:

acoustic treatment: carpets, curtains, doors (and closing doors), soft covers on display tables, ceilings etc
INSET to mainstream teachers re management of hearing loss, use of radio aids and attachments
Auditory Training Units (ATU), conference mics etc
good classroom management
provision of quiet areas
monitoring and evaluating the use of hearing aids (including modern technology eg digital hearing aids)
use of radio aid (RA) transmitter input adaptors and leads
ensuring that deaf pupils classroom is located to preclude intrusive noise from playing fields, roads etc
use of visual clues and access through text.
skilled use of radio aids by deaf pupils:
- knowing when it is working correctly
- being able to assist in fault finding (when old enough)
- being able to decide the situations when a radio aid is useful
- using additional leads and adaptors with TVs, computers etc.
- having confidence to explain use to other pupils and teachers
provision of Soundfleld FM System

"Acoustic treatment to reduce background noise level (BNL) is likely to improve reverberation time (RT). if BNL is controlled then apparently high RT has a minima! effect when a radio aid (RA) is in skilled use and set up properly." Roger Wills, BAAS 29.01.98

The outcomes of severely and profoundly deaf pupils educated in mainstream, unit and resource settings, where BNLs and RTs have not been ideal need to be researched in order to demonstrate the value of the additional strategies that can be successfully used. There are numerous educational and social advantages in attending local mainstream schools and living at home. These should not be underestimated in the overall view of provision. It is important that young deaf adults, whether they communicate in sign or speech, can function in the hearing world as well as the deaf world.