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Restorative acoustic conditioning

(Suomeksi tässä)

Acoustical conditioning as a restorative factor

(A speech given to the local Toastmasters club members)

I open with a strong one-time clap of hands.

2017-11-02 12.11.33

Did anyone hear an echo? No? Well, it was a very quick-responding one. Not a long-ringing echo, such as one can hear in a large room.

In the world of acoustics, and especially noise, I want to present to you 3 case examples of when noise – different forms of noise – is a disturbance to your performance.

Noise is the definition of sound that is perceived as annoying or disturbing.

Before I start with the cases, I wish to present you with the term Acoustical conditioning. Conditioning, here, means various ways to control the sound that we hear around us.

The case examples will show you effects that sound – or noise – has on how well you perform different tasks.

The case examples will also show that a more stable sound-atmosphere can have a restorative effect. Here the world restorative means healing – how fast and well one as a person is returned, back in full energy. For example, after a good night’s sleep.

During my presentation, please check your memory about what kind of noise-related disturbances you may have noticed. Situations, occurring almost every day, that you know you would like to change.

Example no. 1 – The office

Picture this… your workplace in an open office… you are in a state of flow… some desks away a few colleagues are talking … or the sound of someone walking – far away in the hall – you have learned to know who is about to arrive by the sound of the shoes.

As you notice these things, the result is a broken chain of thoughts in your work. If you lost track of what you were doing, you may spend some time to catch your line of thoughts. How many times are you interrupted during the day – how much valuable time are we losing in performance?

One solution could be to wear sound cancelling earphones. Well, these are a good tool for phone or Skype conversations, as this improves your hearing – and doesn’t disturb others if they also wear headphones. However, wearing these also signals a wish of privacy – which you spot from far away. Regardless of busy-light being used.

A far better solution to increased performance in the office world is diffusion of sound. A diffusor is a panel that breaks soundwaves – by scattering these into smaller waves, as these are reflected from the uneven panel surface. As the small waves cross each other in their new paths, they cancel each-others’ energy.

When I say soundwave, think of the surface of a lake where a wave-circle is growing larger as you threw a stone.

A diffusor is a panel based on mathematical design.

( Passing around a piece of wood + Duplo-cube )

As material is fit for purpose any hard surface, such as wood or plastics. EPS, polystyrene or styrox as we say in the Nordics, works as well and is considerable lighter in weight. The key, is a hard surface.

The unevenness is created by many towers of various heights – if picturing the panel laying on its back on the floor. The panel surface profile is similar to that of a city skyline. In order to scatter as many frequencies as possible, the surface irregularity is seemingly random. But it is not!


Ensuring that the surface shape does not repeat itself, is a mathematical formula based on prime roots. Depending on the size of the room volume, the same panel can be applied, produced in several units.

Each tower height (or depth, if study from above) represents a certain frequency – a tone, in other words. Think of a bottle filled with a little water, and you blow air across the bottle opening – add or remove some water, and the tone changes. The science behind this was found by Mr. Helmholtz, whom studied resonating cavities.

By the way, good to know:

For reference, recording studios started to utilize this kind of diffusors in the late 60’s, and since then several known studies has been made. One of the most referred to paper is one done by BBC in 1990.

Example no. 2 – The Restaurant

Following setting… at a restaurant… with your loved one, or with a group of people… you lean in over the table… however it is near impossible to follow what is said from across the table… doesn’t even have to be a large room.

As everyone else in the room is having a hard time to hear their friend at their table, people lean in closer to hear better. As this doesn’t help much, all as a group raise their voices.

Now, how one reacts to this atmosphere is of course highly subjective! Around the Mediterranean and in South America people would probably think it strange if the place would not be intensively lively – and we would expect it as well, to be part of our vacation experience. But, come here to North Europe…

The result is a situation where you may not remember the taste of the food, but rather the restaurant as a place of having a hard time for conversation.

Not a restaurant that you would highly recommend to anyone, although the food was excellent.

One solution could be (very thick) curtains and carpets, but that only does it for a certain distance – in other words, this is not overall effective.

A dampening solution that mineral wool isolation provides is more effective solution. Dampening, in this context, means that a soundwave gets caught up in a material. Trapped, to a high degree. For example, take a 50mm thick sheet of isolation sheet, wrap a textile around it with a photo-print of berries in a forest – and hang it on the wall.

If do go advanced, arrange a 30mm air space between panel and wall (or ceiling).

( Passing around a piece of foam + mineral wool )

Fit for dampening purpose are materials such as isolation or foam that is structurally self-bearing, in other words somewhat stiffer than the commonly found massproduced isolation. The key, is a soft and dense (heavy) material, all the way through.

By the way, good to know:

Most product manuals of mineral wool isolation contain diagrams about sound dampening efficiency. Most interesting in these catalogues, are the diagrams showing that if you allow for air behind the sheet – between the wall and the dampening element – the dampening effect increases drastically.

Why? For 3 reasons:  (and a combination of these)

  1. the increased distance that a soundwave has to travel through the isolation.
  2. the element surface is farther from the wall; remember Helmholtz and the bottle.
  3. the dampening area increases, as the sides of the sheet come to greater use.

Example no. 3 – At home

Anyone have a cinema-theater at home? Perhaps loud and playful children?

A home cinema theater with multiple speakers can be difficult to fully enjoy. This would be comparable with a recording studio with many music instruments, and no acoustic treatment. A good cinema has several dampening solutions. Great cinemas, and rooms for stereo listening, adopt both solutions; dampening and diffusion.

For a child room, a dampening solution is quite sufficient. This works for turning down a notch the felt loudness of screams. And, also keeping you from hearing your own voice echo when reading the bed-time story.

( This frame is 30 mm in depth: the dampening material together with the canvas textile builds to some 40 mm in total, thus hardly seen from the side. )


We can dampen noise through use of material such as isolation, and we can dampen noise through diffusion by reflective surfaces

Be it you alone at your office desk, at a restaurant table with friends, or in your home sofa watching a movie with family;

A bad echo or disturbing background noise where you need to work (or study) can seriously disrupt what otherwise would be an efficient session.

Noise can easily be managed by controlling the physics behind echo. The before-mentioned solutions work in their specific ways, and as exemplified can as well be combined for an improved outcome.

By implementing mentioned ways of acoustical conditioning – dampening and diffusion – you will do better at work and in your studies. This, because of being able to enjoy a better attention to details together with a longer span of concentration.

An unbroken span of concentration is pretty much what I like to call mindfulness. A state of yoga.


I hope I got hold of your attention. You can also recap through a video-presentation of mine, available on YouTube.

Did you come to think about a case that I did not mention, or have another solution in mind – please do approach.

Remember what quietness can do for you, and do test your surrounding at work or at home with a strong hand-clap.



This speech was given at my local Toastmasters club ‘Virtual Speakers Espoo – Hyvinkää’, here improved in writing based on the feedback of my fellow toastmasters.

The manual instructs as follows: a strong opening and conclusion, an outline that can be followed and understood; a clear message with supporting material; appropriate transitions.

#disturbance #performance #acoustics #conditioning #restoration
#echo #speech
#restaurant #mindfulness #yoga
#pollution #noisepollution
#toastmasters #toastmastersfinland #tmdistrict95


About the Author.

Martin R.C. Andersson started out as a mechanical engineer, slowly developing a soft spot for project management in which he worked 10 years.
Although having resigned from a corporate career within project management, the soft spot he keeps alive through a keen interest in room environment treatment. By control of sound and light, looking to tweak for that noise-free listening… which should be a norm.
Values silence, and now and then solitude.
Thinks Mindfulness is a ‘state of being’ when work really gets done.
When thoughts flow – without disruption – to reach either a creative state or finish what’s at hand.

When the outside world is tuned out, performance is tuned in.
Feels best when Minimalism, Functionalism and Art come together, crossing paths.


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