Acoustics in schools: calmer classrooms

In many classrooms, hard ceilings, walls and windows reflect sound for a long time. Anyone talking over this reverberation gets louder, and the class follows suit. Ceiling elements and wall absorbers shorten the reverberation, make speech easier to understand throughout the room and create a calm learning atmosphere.

How loud is it during lessons?

According to Unfallkasse NRW, the average sound level during lessons is 60 to 70 dB(A), and 70 to 75 dB(A) in primary schools.⁶ Levels like these rarely endanger hearing, but they do get in the way of communication. If teachers have to make themselves heard over the noise, the DGUV says their voice and larynx are put under excessive strain.⁴

What reverberation time does a classroom need?

According to the DGUV, classrooms of a typical size should have a reverberation time of 0.5 to 0.6 seconds.¹ The German workplace rule ASR A3.7 sets an upper limit for teaching rooms, T_target = (0.32 · lg V − 0.17) s. For an occupied room of 210 m³, that is about 0.6 seconds.² If pupils with impaired hearing take part or lessons are taught in a foreign language, it should be 0.4 to 0.5 seconds.¹ For this, DIN 18041 specifies the inclusive usage type A4 with T_target = (0.26 · lg V − 0.14) s.³

What does less reverberation achieve?

In a field study with 487 primary school children from 21 classes (reverberation times of 0.49 to 1.1 seconds), children in reverberant rooms did worse at understanding speech and remembering spoken content. They also rated their relationships with classmates and teachers less positively.⁵ The DGUV reports level differences of up to 13 dB between acoustically good and poor classrooms, and significantly fewer signs of stress among teachers.⁴

Noise control in schools: room acoustics or sound insulation?

“Noise control in schools” covers two different tasks. Structural sound insulation keeps out noise from neighbouring rooms, the corridor or the street: airborne sound through walls and doors, impact sound through floors and ceilings. The benchmark for this is DIN 4109 “Sound insulation in buildings”; walls, ceilings, doors and windows are responsible for it — and therefore the school authority, in new builds or refurbishments. Room acoustics make sure that sound does not reverberate for long within the classroom itself. The benchmark here is acoustic quality under DIN 18041 “Acoustic quality in rooms”.

Much of the noise in a classroom is created in the room itself: conversations, chairs scraping, footsteps, the teacher's voice. In a reverberant room, this background noise mixes with speech and the noise level keeps building up. Sound absorption on the ceiling and walls helps against this — with no building work, and it can be retrofitted while lessons continue. Sound absorbers do little against sound from the room next door, however. If you need sound insulation between classrooms, structural improvements are required.

Noise control in canteens and music rooms

In the canteen, lots of pupils, crockery and hard surfaces come together. Without sound-absorbing surfaces, the noise level rises by the minute, because everyone speaks louder to be understood. Ceiling absorbers above the tables shorten the reverberation and turn the break back into a break.

A music room needs different acoustics from a classroom. DIN 18041 lists music as its own usage type, A1, with a longer target reverberation time than teaching (A3). If a music room is over-damped, instruments and choirs sound dull. That is why we don't plan music rooms by rule of thumb, but with the actual room data. If the main aim is that neighbouring classes don't hear anything, sound insulation under DIN 4109 is needed as well.

Which solutions suit schools?

The ceiling is the first choice: the DGUV names a sound-absorbing ceiling area as the way to reach the target values.¹ Suspended ceiling panels can be retrofitted without building work. In teacher-led lessons, wall absorbers on part of the back wall can improve intelligibility for the front rows.⁴ Corridors, stairwells, break halls and assembly halls should also be designed with room acoustics in mind.⁷ We check reaction to fire, mounting method and the requirements of your federal state before we send a quote — find out more under Acoustic panels and fire safety.

Sources (in German, except no. 5)

1. DGUV Regel 102-601 Branche Schule, 2019, p. 43
2. ASR A3.7 Lärm, March 2021 edition, section 5.2.2
3. DIN 18041:2016-03, usage type A4, cited in DGUV Sichere Kita: Bau- und Raumakustik
4. DGUV Information 202-090 Klasse(n), Räume für Schulen, October 2018 version, pp. 21 and 22
5. Klatte, Hellbrück, Seidel, Leistner: Effects of Classroom Acoustics on Performance and Well-Being in Elementary School Children, Environment and Behavior 42 (2010), pp. 659–692
6. Unfallkasse NRW: Lärm-Akustik-Belastungen in Schulen, Prävention in NRW 79, p. 2
7. DGUV Regel 102-601 Branche Schule, 2019, pp. 27, 54 and 64