EDUCATION
EVERY CLASSROOM CAN BENEFIT FROM A SOUND FIELD SYSTEM
Adding a soundfield system provides significant speech-in-noise recognition improvements for normal hearing children: up to 28% at 65 dBA of noise and 50% at 70 dBA over no soundfield (2).
Phonak Roger Touchscreen Mic and Digimaster 5000v2 speaker used in the classroom
sound field systems in the classroom
- Large numbers of studies have documented measurable results in student achievement and attentiveness in classrooms that use sound field (MARRS, 2005; Flexer, 2002; Long, 2001). In 2002 a study was done of 626 primary school children in Rotorua (1). They were split into two groups: Intervention (438 students in 30 classrooms) and Control (188 students in 12 classrooms ). The Intervention classrooms were fitted with sound field speaker systems whilst the Control classrooms remained un-amplified.
- The study found:
- - Sound field dramatically improves listening and reading. - Sound field dramatically improves phonologic skills. - Increased on task behaviour. - Improved understanding of instructions. - Improved student cooperation. - Students find it easier to hear. - Reduced disruptive behaviour. - Reduced vocal strain for teachers. - Improved listening comprehension for students with middle ear dysfunction. - Enhanced classroom harmony. - High acceptance of sound field by teachers. - Quieter classrooms.
.jpg "PAT scores showing very significant improvements for the Intervention")
PAT scores showing very significant improvements for the Intervention group. From Heeney, M, 2004
.jpg "Phonological awarness tests showing significant improvements for the I")
Phonological awarness tests showing significant improvements for the Intervention group. From Heeney, M, 2004
Signal to noise ratio in teaching spaces
It is estimated that 75% of the school day is spent engaged in listening activities (3). However, classrooms are noisy environments and occupied classroom ambient noise levels range from 64 to 72 dB(A)(4). Classrooms in New Zealand frequently exceed 70 dB(A) when occupied (5).
For effective classroom learning of typically developing children, the Signal to Noise Ratio (SNR) of the teacher’s voice should be +15dB or better (6). And with normal speach being 65dB, a teacher will have to continually raise their voice by at least 15dB for students to achieve good speech recognition over a 65dB(A) ambient noise. As the ambient noise increases, so too must the volume of the teachers voice. At an ambient noise level of 70 dB(A) a teachers voice must reach 85 dB(A), which is the volume of a food blender or vacuum cleaner. 85 dB(A) is also the volume at which hearing protection begins to be required in the work place. Worksafe NZ specifies that under NZ law employers must, so far as is reasonably practicable, make sure that no workers (or people that visit the workplace) are exposed to noise levels equivalent to 85 dB(A) averaged over 8 hours.
As the distance from the teacher increases, the volume of the voice fades. Every time the distance from the teacher doubles, the volume decreases by 6dB. So if a teacher is talking at 75dB in a classroom with a 60dB ambient noise, then the SNR at one metre from the teacher will be +15dB. At two metres the teachers volume is now 69dB, so the SNR is +9dB. At four metres the teachers volume is down to 63dB, so the SNR is +3dB. As many classrooms are up to ten metres long, we can see that only the students immediately in front of the teacher will get a favourable SNR.
This means that many students with normal hearing will struggle to hear well in a normal classroom situation. Students with any hearing, attention, or learning difficulties will struggle further. Teachers also suffer, with voice strain injuries common, especially among new graduates. A University of Auckland survey of 1,879 teachers in 2015 found: - A third of participants developed a voice disorder during their teaching career with around 13% having a vocal issue on the day of the survey. - 24.7% reported voice problems over the year. - 47% reported voice problems were moderate to severe. - More than a quarter of teachers had stayed away from work for 1-3 days due to a vocal problem.
For effective classroom learning of typically developing children, the Signal to Noise Ratio (SNR) of the teacher’s voice should be +15dB or better (6). And with normal speach being 65dB, a teacher will have to continually raise their voice by at least 15dB for students to achieve good speech recognition over a 65dB(A) ambient noise. As the ambient noise increases, so too must the volume of the teachers voice. At an ambient noise level of 70 dB(A) a teachers voice must reach 85 dB(A), which is the volume of a food blender or vacuum cleaner. 85 dB(A) is also the volume at which hearing protection begins to be required in the work place. Worksafe NZ specifies that under NZ law employers must, so far as is reasonably practicable, make sure that no workers (or people that visit the workplace) are exposed to noise levels equivalent to 85 dB(A) averaged over 8 hours.
As the distance from the teacher increases, the volume of the voice fades. Every time the distance from the teacher doubles, the volume decreases by 6dB. So if a teacher is talking at 75dB in a classroom with a 60dB ambient noise, then the SNR at one metre from the teacher will be +15dB. At two metres the teachers volume is now 69dB, so the SNR is +9dB. At four metres the teachers volume is down to 63dB, so the SNR is +3dB. As many classrooms are up to ten metres long, we can see that only the students immediately in front of the teacher will get a favourable SNR.
This means that many students with normal hearing will struggle to hear well in a normal classroom situation. Students with any hearing, attention, or learning difficulties will struggle further. Teachers also suffer, with voice strain injuries common, especially among new graduates. A University of Auckland survey of 1,879 teachers in 2015 found: - A third of participants developed a voice disorder during their teaching career with around 13% having a vocal issue on the day of the survey. - 24.7% reported voice problems over the year. - 47% reported voice problems were moderate to severe. - More than a quarter of teachers had stayed away from work for 1-3 days due to a vocal problem.