Voice problems are a health threat to teachers

Teachers have to shout as loud as a freight train (at 80-85dB) in order to be heard over the average noise level of 64 dB in classrooms without acoustic treatment.

This leads to voice disorders. Although teachers only make up a small percentage of the workforce, studies measuring vocal problems in workers consistently find teachers to be overrepresented.

Class A sound absorption has shown to lower the classroom noise by 10 dB cutting the perceived noise level in half. This means that nobody has to shout in order to effectively teach, hear, understand and learn.

Consequences of voice problems on teachers working life

(Study ran 1 year, featuring 2400 participants)

Challenging assumptions about noise in classrooms

Researchers made groundbreaking findings that most noise in school classrooms was not caused by the assumed noise from planes, trains and automobiles, but by the students themselves during learning activities.

When installing in Class A sound absorbing ceiling they found that the result was way better than expected. The theoretical absorbing properties of the ceiling was 3 dB.

However, the real change was in the behavior of the people in the classroom. Since everyone could be heard and understood without raising their voices, students and teachers immediately spoke more quietly. In fact 7 dB more quietly, with a total reduction of 10 dB cutting the perceived noise level in half.

Studies have shown that a reduction of classroom noise has a positive effect on mood, stress levels, and most importantly, learning abilities.

How noise affects our mood

It’s widely accepted that noise affects our ability to learn and understand. But studies have also found that it affects our mood and behavior. One study measured how annoyed students got in classrooms with different reverberation times (RT). Long RT affects speech clarity and you typically need to raise your voice to be heard. When one person starts speaking louder everyone else follows suit leading to an upward spiral in noise levels.

The moods of the students were clearly affected by the longer RT with a clear impact on student-teacher relations.

Class A sound absorption reduces RT and absorbs sound -3 dB. It also has a positive effect on student behavior; with less reverberation students tend to lower their voices -7 dB. In total a 10 dB reduction cutting the perceived noise level in half.

This has a proven positive effect on students’ mood, stress levels and learning abilities.

Lowering student annoyance by lowering reverberation time (RT)

Comparing the percentage of “correct” responses to the question “Classmates behave noisily” (asked when the RT is low, medium or high) shows that students notice noisier behaviour as the RT increases.

Good acoustics lower heart rates

When it was realized 80% of teachers were stressed by noise, researchers decided to find out if these stress levels could be reduced by improving the sound environment.

They also sought to discover how classroom noise actually affects teachers and students during activities.

The result? With Class A absorbing acoustic treatment, teacher heart rates calm down by 10 beats per minute (bpm)

How it’s possible

If a classroom has poor acoustics, sound is amplified as it bounces off the reflective ceiling and walls. This creates background noise which distorts speech. This environment will often feel progressively more stressful as the class (or day) continues.

“Heart rate is a medical recognised stressor.”

- Dr Gerhart Tiesler

Reducing noise and reverb reduces stress

Acoustical treatment transforms educational spaces into more relaxed environments where everyone feels calmer. This results in lower noise levels as well as heart rates.

Noise in relation to voice

To understand what is said in a classroom speech needs to be heard clearly above the background noise. This relation between speech and noise is called signal-to-noise ratio (SNR) and the difference between signal and noise is measured in decibels (dB).

The average noise level in a classroom without sound absorption is 64 dB which makes it very difficult to achieve a satisfactory SNR of 15-20 dB. The teacher would have to shout as loud as a lawnmower (85 dB) to be heard.

Class A sound absorption is proven to lower the classroom noise by up to 10 dB cutting the perceived noise level in half. This affects SNR and speech intelligibility positively, making it easier to talk, hear, understand and learn.

Younger learners need bigger signal-to-noise ratios

In a speech intelligibility study, it was found that while 15 dB could be considered a satisfactory SNR for the older children (age 11), the youngest children (age 6) required an SNR of 20 dB to provide adequate speech intelligibility.

Therefore, younger children and also children with additional listening needs are vulnerable listeners that stand to benefit the most from acoustic treatments that increase the SNR and make the learning environment more accessible for all children in it.

Noise interferes with cognitive processing

It’s easy to understand that a noisy classroom makes it hard to hear, but studies have found that it also makes it hard to think.

One study had students perform standardised tests in English and Math in rooms with different noise levels. The results showed that increasing the noise levels to those found in ordinary classrooms clearly lower the scores in both subjects, with a more dramatic impact on English.

The study did the same tests with students with special education needs (SEN). This not only includes hearing loss but also those with attention problems and those learning in a second language.

The results show children with special educational needs were more negatively affected compared to regular learners. Especially when levels reached 65 dB.

Sadly, standard noise levels in classrooms without sound absorption are 64 dB on average making the need for good sound absorption evident. For students in general, but maybe more importantly, for an equal learning environment where all students have a chance to shine.

Voice problems in teachers

For children to hear a voice properly when there is background noise in a room, the voice needs to be a lot louder than the background (about 15-20 dB louder). The average background noise in most classrooms without acoustic treatment is 64 dB. That means teachers have to shout as loud as a power drill (80-85 dB) in order to be heard.

This leads to voice disorders. When comparing the number of vocal disorders in teachers with the rest of the working population, results show that teachers have a far higher number of issues than other types of workers. For example, one study found that 32% reported vocal problems compared to the non-teacher group, where only 1% experienced problems.

Far higher incidences of vocal harm have also been recorded. Another study found up to 65% of teachers surveyed reported symptoms of vocal strain compared to only 2% in non-teachers.

This clearly shows that teachers’ voices are working in overdrive to be heard above the classroom noise. Based on numerous studies on teacher vocal health, teachers are at least twice as likely to have voice related problems versus other occupations.

Why people raise their voice over coffee

Almost everyone has experienced this phenomenon. It occurs when a group of people talk in a noisy environment like a cafe, party or classroom. When subjected to background noise, people involuntarily change the way they speak, increasing volume, frequency and intensity. When one person starts speaking louder, everyone else follows suit, leading to an upward spiral in noise levels.

This effect can be reduced using good sound absorption. Research has shown that a Class A sound absorbing ceiling, with a theoretical dampening effect of 3 dB, influenced students to lower their voices with an additional 7 dB. This total of 10 dB reduction cuts the perceived noise level in half. This reversed cafe effect is sometimes called the library effect.

Studies have shown that a reduction of classroom noise has a positive effect on mood, stress levels and learning abilities. It also prevents voice disorders and helps with speech intelligibility.

How noise affects test results

High classroom noise levels have a negative effect on students test results.
This has been proven in a number of studies.

In one example, researchers compared test results of primary school students in two different settings. One with quiet background noise and one with normal activity babble noise found in most classrooms or around 65 dB.

It showed that typical classroom noise had a significant impact on language and cognitive test results.

In another study, student accuracy on a speech perception task improved by 35% with the introduction of a Class A sound-absorbing ceiling and wall panels. The installation reduced the noise level by up to 10 dB, cutting the perceived noise level in half.

“Staff working in the treated classrooms say there’s an enormous difference. Not only do they not have to shout to be heard, but there’s generally a calmer, quieter and more relaxed atmosphere.”

- Head teacher Miss Catherine Douglas of Balgreen Primary School