According to the World Health Organization, background noise should be below 35dB. In Bulgaria, the permissible equivalent level is 40dB. Why does the acoustic environment in our classrooms not meet international recommendations for effective learning?
A motivating teacher, curious students, and an environment that encourages curiosity, dialogue, and collaboration. According to many, this is sufficient for creating an effective learning environment. The truth is that this learning environment also depends on the acoustics of educational institutions. Noise is often underestimated as a factor that harms not only concentration but also student motivation. Numerous studies point to noise as the main cause of low academic achievement, irritation among students and teachers, and deterioration in teachers' health.
What are the official standards for acceptable noise levels in classrooms?
In Bulgaria, the permissible equivalent noise level in classrooms is 40 dB(A). This is stipulated in Regulation No. 6 of June 26, 2006, and applies to primary and secondary schools as well as university lecture halls.
The World Health Organization sets stricter standards, recommending that background noise be below 35 dB(A) to ensure normal speech perception and concentration.
Engineer Alexander Kirechev, founder of Acoustic Force, shares: "The comparison shows that Bulgarian standards are less strict than international recommendations. According to our official framework, classrooms can be noisier than optimal for effective learning."
How does noise affect teachers and students?
Ein Bericht von Ecophon, der auf langjährigen Studien von Bridget Shield basiert, zeigt, dass Lehrer, die täglich mit schlechter Akustik in Klassenzimmern konfrontiert sind, anfälliger für Gesundheitsprobleme sind. Über 65 % der an den Studien teilnehmenden Lehrer hatten Probleme mit ihrer Stimme, und 80 % von ihnen waren Lärmstress ausgesetzt.
Good communication in the classroom requires the teacher's voice to clearly dominate background noise. Research shows that for complete intelligibility, the signal-to-noise ratio (voice to background) must be at least +15 dB. A teacher's normal speech is about 55-60 dB at a distance of 1 meter. To ensure intelligibility, background noise should not exceed 40-45 dB," commented Eng. Kirechev.
Different acoustic conditions also affect students. When noise reaches ≈50 dB, comprehension begins to decline sharply—they can no longer clearly perceive every word. Their concentration decreases dramatically at higher noise levels, but disruptions in discipline are also observed. Noise has a negative impact on learning outcomes.
Australian scientists report up to a 33% decline in academic performance due to poor acoustics, and National Academies Press reports that children in noisy school environments fall behind by about two months in their reading level.
Background noise in the classroom hinders students' academic performance.
How can we achieve a better acoustic environment?
A good acoustic environment can completely transform the learning process for both students and teachers.
"Optimal acoustic design has two goals: to reduce background noise and control reverberation (echo) so that speech is clear at every point in the room. This can be achieved through acoustic ceilings, wall panels, and sound insulation. Depending on the type of room, we at Acoustic Force can offer specific solutions for small and large classrooms, university lecture halls, as well as rooms with high ceilings," says Eng. Kirechev.
Good acoustics create a quieter and calmer school environment, reduce conflicts, and increase student motivation. They improve discipline and facilitate active participation in class. Noise in the classroom is an invisible but constant enemy of concentration. Improving acoustics through proper design and sound insulation can make the learning environment quieter, more effective, and healthier for both students and teachers.
