Acoustic correction of a classroom: an essential condition for schools and universities

Correzione acustica aula didattica - Caruso Acoustic

Project: Classroom of about 90 places
Room size: 410 m³
Acoustic problem: High reverberation times due to reflective surfaces

The efficiency of oral communication in a teaching context, and therefore in a learning process, is closely related to the acoustic conditions of the environment. In the acoustic design of classrooms and lecture halls, many factors that may affect the speech intelligibility, as the STI (Speech Transmission Index) and the %-ALCONS, must be taken into account. STI is the measure of speech intelligibility with values between 0 (utterly incomprehensible) and 1 (perfect intelligibility). ALCONS, instead, expresses the articulation loss of consonants; low values mean a high level of intelligibility. In places whose intended use is related to learning, the value should be at least 5% or less.

The proposed acoustic correction project concerns a classroom of 108 m² with a capacity of about 90 places. This space is characterised by very reflective surfaces, such as plaster walls and ceiling, as well as the parquet floor. This results in a reverberation time (Rt) of 1.73 s at an average of 250-2000 Hz in occupied room, too high for teaching activities.

Distribuzioni pannelli fonoassorbenti aula didattica

As shown in the graphs, it is possible to reduce reverberation times with the installation of hanging and wall-mounted Silente sound-absorbing panels. Hanging Silente panels are positioned on the ceiling with a U-shaped arrangement, while the wall-mounted ones are placed on the back wall of the room.By comparing the data, before and after the acoustic correction, a significant improvement of Rt, from 1.73 s to 0.55 s, can be noticed. Consequently, a considerable improvement of the two parameters expressing the speech intelligibility, such as the STI and ALCONS, can be achieved. Indeed, the STI goes from a normal condition value of 0.53-0.55 to an excellent value of 0.74-0.77. %ALCONS has improved too, with values of 3-4 %.

Silente sound-absorbing panels are the best solution to solve acoustic problems concerning the speech. The high level of customisation, from fabric colours and prints to the integration of LED lighting systems, makes them adaptable to any space and furniture.