Abstract:
High levels of noise have been shown to be detrimental to young children when language and discrimination skills are developing. In particular, this applies to children who attend Early Childhood Education (ECE) Centres who are exposed to excessive amounts of environmental noise. Ambient noise can include the children themselves, ceiling fans, the hum of lights, road traffic noise from the outside, and heating and ventilation systems. Because of the potentially high levels of exposure to children and teachers there has been interest in developing guidelines and strategies to reduce the noise levels in classrooms. Recently, the National Foundation for Deaf (NFD) in New Zealand has developed the Safe Sound Indicator (SSI) as a tool for controlling the noise levels of preschool classrooms. The device is called a ‘noise traffic light’ and indicates (via orange or red lights) when the sound levels exceed acceptable levels. The aim of this study is to evaluate preschool classroom acoustics in order to determine the optimum settings for the SSIs depending on the environment. Currently, the prototype device is set to trigger at a level of 80 dB for green, 85 dB for orange and 90 dB for red. To investigate the optimal trigger levels, six ECE centres in Auckland were selected for comprehensive acoustic analysis. With respect to the measured unoccupied background noise levels, none of the classrooms in the six ECE centres studied were found to be acceptable (less than 35 dBA) according to the recommendations. The reverberation times were significantly in excess of the recommended 0.4 sec or less, except for one, which had the smallest classroom dimensions. The current study found that the average noise levels in occupied preschool classrooms were around 70 dB LAeq. However, there was a variation in noise levels depending on the activities: ‘arrival’, ‘mat time’, ‘free play’ and ‘meal time’. It has been found that there were several factors affecting the classroom noise level such as weather, number of children (occupancy) and teaching strategies (dividing into a small group work). Teacher’s daily noise exposure was also investigated in the six ECE centres. The mean eight-hour noise levels ranged from 76.2 to 84.5 dB LAeq. The SSIs can be used for educational purposes during ‘meal time’ or ‘mat time’. However, the internal/external background noise via possible acoustic treatment must be considered with the introduction of SSI as suggested by NFD. The current trigger levels seemed to be defined by NIHL risks and related to peak levels rather than steady state classroom noise. Thus, the future study to evaluate the effective use of SSIs should involve trialling different settings with various activities and centres. This will lead to a further understanding about the optimal settings to affect children’s behaviour in response to noise.