Differences of classroom acoustics are discussed appropriately. Based on observations of 175 lessons the effects of room characteristics (e. g. increased absorption, shortened reverberation time and improved speech intelligibility) on basic and working sound level in the context of each kind of work during lessons will be discussed. A methodical examination of the database allows an assessment of mean values but also of the detailed teaching phases, as characterized by certain pedagogical factors. Therefore, it is possible for example to evaluate the effects of frontal teaching in contrary to differentiated lessons.
The results provide the basis for discussions on stress level and work demands of teachers. It has been proved, that the heart rates of teachers are coupled to the stress reaction to the noise level. Students show the same reaction. By monitoring all actions of teachers and students during the lessons it is now possible to analyze further on the impact on social behaviour depending on the acoustical conditions of classroom working.