Elementary school Pod Skalkou in Rožnov pod Radhoštěm goes hand in hand with modern times. In order to ensure the best possible understanding in lessons and to increase the effectiveness of education, the school is also trying to improve its premises. Teaching is not only about qualified personnel, but also about the technologies used and the equipment of school classrooms. In one of the classrooms, the school decided to install SilentMax acoustic panels to improve the conduction of sound and speech. The results were audible almost immediately.

Class 6.B has internal dimensions of 8.6 x 6.6 x 3.35 m, where two lintels of 53 x 26.5 cm pass through the ceiling. Emotionally, the space can be characterized by a considerable echo and incomprehensibility of the spoken word.

Silentmax® acoustic panels were installed in a triangle between the ceiling and the lintels so as to visually interfere with the appearance of the classroom as little as possible. Laths were anchored to the lintels and the ceiling, into which the panels were attached using handles. Four acoustic absorption areas with a total area of 14.9 m2 were thus created.

Measurement of the acoustic properties of the space

A calibrated UMIC microphone and REW software were used to measure the acoustic properties of the selected class. The measurement was performed twice in total – before installation and after installation. What are the results?

Waterfall – reverberation time

It shows the intensity of acoustic energy depending on the frequency and reverberation time. The value of the acoustic energy in dB is represented by the Y-axis. The frequency from 100 Hz to 10 kHz is represented by the Y-axis. The time, or reverberation time, is represented in space by the Z-axis. In half a second, the Z-axis ends, at this border an area corresponding to the value of the acoustic energy in time is visible 0.5 s.

RT60 – reverberation time

It represents the time in which the acoustic energy value drops by 60 dB. Time is represented by the Y axis. Frequency in the range of 100 Hz to 10 kHz is represented by the X axis. At a frequency of 1 kHz, after the acoustic panels were installed, the reverberation value dropped from 1.516 s to 0.658 s, which represents a 57% reduction in reverberation.


The installation of an acoustically absorbing surface with a total surface of 15 m2 reduced reverberation by 57% (at an average frequency of 1 kHz). The echo was reduced by more than half. The intelligibility of the spoken word has fundamentally increased and the overall noise in the classroom has decreased.

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