The complaints about heavy noise pollution in educational institutions were the cause to cast a light on the possible causes and consequences of "school noise". In this context the present study cast a light on the topical educational trends and the connected kind of work and communication behaviour in the classes by means of two elementary schools

• Grundschule Stichnathstraße: 1. to 4. year, 2 classes per year with different room acoustic conditions (first floor: RT > 0,5 s and sond floor: RT < 0,5 s)
• Baumberge-Schule: 2. year, before and after room acoustic redevelopment.

In the first place it is analysed how the different kinds of work (frontal lessons vs. differentiated lessons) have an effect on basically (L_A95) and working sound pressure level (L_Aeq) in the classroom, on the basis of 175 lessons. In the second place it is investigated how an altered room acoustic (reverberation time and speech intelligibility) has an effect on the sound levels in context with each kind of work. The results provide the basis for the further question which deals with the influence of room acoustic conditions on the teachers' measurable physiological load depending on class events, kind of work and speaking parts. Among other things the analysis shows:

1. A reduction of sound pressure level up to 5 dB at frontal lessons and 12 dB at differentiated lessons (9 dB follow from changed student behaviour) can be proved on the example of redevelopment.
2. Under improved room acoustic conditions the physiological load decreases at 3 heart beats per minute in average. In comparable situations a single person's load decreases up to 10 heart beats per minute, fatigue processes decrease too.

Altogether, with room acoustic improvement the work conditions improve, the sound level decreases, the students' social behaviour becomes calmer, the teachers experience a lower load at increasing activity and at the same time a lower sensitivity with regard to the sound level.