At EIAS 2023, findings from the former ISF (institute for interdisciplinary school research) and Gerhart Tiesler were presented by Rainer Machner. The research was initiated in 2005 by public discussion of air quality in offices and schools. One pattern for the research we found in “Handbuch der Schulhygiene” (handbook of hygiene in schools), 2nd edition from 1902. Most of the results in that book were forgotten, especially recommendation of the limit of 1000ppm CO2 in the air of classrooms for good learning conditions.This lead to the focus on Acoustics and Air Quality – The Impact on Student Concentration and Fatigue.
This recent research included monitoring of complete lessons over the day in two elementary schools and one gymnasium. This included an awareness-test before and after school. Monitoring has been done over two days in every group participating, divided in two steps. First step under usual conditions, second step with special timing of ventilation of the classroom. For best comparison conditions monitoring was placed for both steps on same weekdays with same timetable of lessons. The data include 16 groups, age from 6 to 16 years old, 350 students.
Continuously monitored data all over the day: CO2, SPL, teaching situation (communication, action), physiologic workload. Awareness-test for every student before an after school day Acoustic-ergonomic data of all classrooms.
Research data monitored
The research data will show the importance of good air quality and room acoustics for better learning conditions. Based on three research projects with data from more than 700 school lessons. The data included:
- Protocols of activity
- Protocols of communication
- Sound pressure level
- Indoor climate
- Workload reaction
- Room acoustics.
Following some of the findings, it is highly recommended to take a look at the full research at the institutes website (in German): https://www.isf-bremen.de/publikationen/forschung/
When it comes to noise and room acoustics, the example from an elementary school with 8 similar classrooms on two floors, with different acoustical treatments, show the effect of the acoustical environment. The “basic sound level” is the mean value of one week of monitoring during lessons, same students and individual teachers:
Interestingly, the effect of improved room acoustics in context of pedagogic relevance was also found. For this investigation, a classroom with compliant room acoustics was refurbished to fulfil the acoustical standard in Germany DIN18041:2016-03 for inclusive teaching.
Monitoring of the teaching process has been done for one week before and one week after refurbishment. The type of teaching „direct teaching“ and „student centered teaching“was monitored during this time. A 3dB reduction of LA was calculated. The actual measured reduction of 13.3 dB by change of behavior, induced by lowering RT from 0.7 to 0.4 sec. This means an important influence on pedagogic process.
An additional workload is caused by noise. Overall, monitored heart-rates (HR) of teachers during lessons were registered continuously, and at the same time the noise levels were recorded.
There is a very high correlation between HR of the teacher and noise level during the lesson. Not only for the person shown in the following results, but also for all teachers.
At one school there was a special research situation: during both weeks, there was the same teacher for all lessons. Also, the students and the timetable was the same. So it’s very expressive to compare both teaching situations. Comparing mean values of HR and Working noise level LAeq there was a big difference found in HR reaction on noise. An increase of LAeq by 10dB(A) generated an increase of HR by 10 beats/min in the room with RT 0,7sec. Whilst, there was only 4 beats/min in the refurbished situation with RT 0,4sec.
Student Concentration and Fatigue
Since it wasn`t permitted to monitor the HR of students, another sign of fatigue, the basic noise level LA95, e.g., restlessness was measured.
At the school with the refurbished classroom. There was a dramatic increase of LA95 under a bad acoustic situation over 5 lessons during the day.
Stopping the noise build up over the day
Monitoring the whole pedagogic process was also done by continuously registering all actions:
– teacher-generated speech
– student-generated speech
– direct teaching (in front of class)
– student-centered teaching (students together)
– Dialog (intensive discussions)
Ratio of these parameters are nearly the same, except dialog (higher under good room acoustic conditions).
Influence of ventilation and air quality on the working sound levels
In the last research, the effect of air quality in classrooms on teaching process was analyzed. In 12 classes, we monitored the teaching process and climate over 4 days each. 2 days as usual, 2 days with a 2min ventilation break at mid of the lesson.
Summary of all monitored lessons with usual working conditions shows ratio of time under good (green), acceptable (yellow) and bad air (red) CO2 conditions.
The working situation changed to much better conditions with a 2min ventilation break in the middle of the lesson. Without the 2 min break, they were in the mean 15 min with „distortion of perception “. With a (ventilation) break of only 2 min there is a benefit of 15 min of “better learning time” in the usual 45 min school-lessons. Another sign of this lowering of fatigue and also a benefit for the teaching and learning situation. This was found to much reduce „dysfunctional activities“ (disturbing the lesson):
Dysfunctional activities can arise as a result of decreased student concentration and fatigue. The study divided all classrooms by RT less and more than 0.6sec. It also looked at “good” and “bad air quality” in context of noise levels leading to:
LA95 reduced for both classes about 1.3 and 1.6dB
LAeq was reduced 0.6dB in classrooms with RT>0.6sec, in rooms with RT<0.6sec reduced by 2.9dB.
There is an effect by air quality, but the influence of acoustics is more important!
Good acoustics is a measurable ergonomic factor and contributes to better human working conditions regarding student concentration and fatigue in school environments!
Sincere thanks to Gerhart Tiesler for decades of research, the findings, the results. This has been a great inspiration for many researchers and the contribution to the improvement of the acoustic ergonomic factors in schools.
Watch the EIAS2023 presentation here.
More info about EIAS2023 here.
More about the Bremen Study regarding – Heart rate as a medically recognised stressor where noise reduction gave teachers a significant long-term benefit.