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Acoustics for Schools and Colleges

I’m going to structure this post in an FAQ format.

Q: We never had a problem with acoustics when we were growing up. Despite not having acoustically treated classrooms, we heard our teachers just fine.  Why worry about classroom acoustics now?

Educational Institutes earlier did not have a few issues that they face now. Here’s what’s changed:

  • Diminishing Playgrounds: The school I studied in had place for football, basketball, tennis, garden, swings for children, a huge auditorium, and even a mini-zoo. The classrooms were in a central building, separated by the main roads by these sports areas, and the school as such was located in a residential area. In contrast, these days, with land prices shooting through the roof, there are plenty of schools in Bangalore with no playgrounds, let alone garden spaces. They either just don’t have one, or they use a municipal ground nearby as their own. I’ve taught in a 30ft long class, at the end of which was 4 ft of external corridor, and then (gasp!) the main road. With the last benchers being 4 feet away from traffic, and 30 ft away from the voice of their teacher, I wonder what they managed to learn. They strained their ears all day above the muffling effect of traffic noise.
  • Road Traffic Noise: The above problem is compounded by the fact that roads are no longer quiet. There is more traffic, more honking, and louder horns than ever.
  • Air Traffic Noise:If anything, air traffic has increased in the 20-odd year span that has passed since I went to high school. All the big cities, some of the smaller cities have all got airports. I’ve sat in the most beautiful lung space in Bangalore – the Lalbagh – and watched 15 flights go above my head in one hour. It’s a bigger problem than we think.
  • Changing Interiors Trends:  These days, the interiors are all sleek, with vitrified tiles commonly in use,  with tables and chairs also having sleeker, smoother finishes. These surfaces reflect much more than materials that were used in older buildings.

Q: So what problems (that I need to worry about) do these building environments cause?

Reverberation:  This is a double edged sword. Too much of it, and the room sounds forever noisy, noise just doesn’t die down, the mood is abuzz, instead of calm. The room makes some voices stand out more than others.  Too little of reverberation, and the room sounds dead. Everyone tends to strain to speak louder.  In both cases, at least the teacher ends up with a raspy voice at the end of the day. It doesn’t just stop with throat irritation ( that persists even during non-teaching hours).  When you’re in a chaotic environment, your heart rate’s always higher. This means your body doesn’t feel calm. You lose quality of life right there, let’s not even talk about after-hours fatigue. Teaching ceases to be enjoyable right then.

Poor audibility : Teachers often have to shout to be heard over the ambient background noise. This volume is often too loud for the front benchers, and usually not enough for the back benchers – leading them to be distracted and disengaged. Teachers are all too familiar with the buzz of conversation in the back benches, when they’re distracted.

Extra boominess : In the same room, some pitches sound very loud, and some pitches sound very soft.  Male teachers with low pitched voices will often find that, there are sometimes spots in the room where their voice sounds too loud, or faint.

Low speech intelligibility: You hear the teacher’s voice booming around you, but you can’t make out the words very clearly. There’s enough research out there for you to look up, and that’ll make you realize that there are schools where students miss out on close to 50% of the speech.  There’s a nervous irritability that sets in when students are not able to understand despite their focus.

Q: This is tricky ground. You could easily be talking through your hat. Is there any way to know for sure that learning is impeded by poor acoustics? Is there proof?

It is true that the concentration ability of all students is not the same – there are always those who concentrate well, and those who get distracted easily. However, organized studies have been conducted – some for as long as three years – to obtain unbiased proof of the effect of bad acoustics on learning – all other factors remaining the same. There is a genuine link because the act of ignoring the existence of a noise source also uses up cognitive power.  A few if them are listed below for those interested. I will not go into explaining what each one says, because these only substantiate what I’m saying.

  1. : This study by the BBC conducted as early as 1999 was conducted for nearly three years.
  2. : This study speaks of vocal strain,  classroom acoustics, and substantiates it with measurements conducted before and after acoustical treatment.
  4. : This last one contains a set of articles regarding current standards recommendations.

Q: How can acoustical treatment help?

In places where the spoken word is the main purpose, acoustical treatment should be considered as important as other aspects of building design. But to keep things short, the improved hearing experience will surely bring benefits – some obvious, and some intangible but important nevertheless.

  • Less vocal and physical strain, more quality of life for teachers.
  • Better comprehension, less disengagement, more active participation
  • Better behaviour due to less frustration. The social effect is the most important, and the least readily tangible.

Q: I don’t understand acoustics. What does a 10dB loss mean? Can I hear some examples please?

The links below have sound samples that tell you what some classrooms sound like, and what they should sound like.

A wonderful talk by Prof. Trevor Cox, speaking of what just a 10 dB reduction in noise levels can do for your understanding.

Another talk by Julian Treasure, discussing the academic, physiological, and social implications of better acoustics in classrooms.

The cost implications of treating a room is surely smaller than the huge profits that many schools in Bangalore rake in. The benefits are huge. I will post another article on the kind of treatment required for speech enhancement. For now I hope people reading this are at least aware that acoustical treatment can significantly enhance the listening experience at places that exist entirely for this purpose.

A quiet environment allows the mind to freely explore ideas, thoughts, and form quirky connections in the head. A noisy environment disturbs not only the mind, but also the body.

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