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My product design final year project on acoustic treatment
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casual-p
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2nd February 2010
Old 2nd February 2010
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My product design final year project on acoustic treatment

Hi everyone,
I'm a third year Product Design Student at the University of Nottingham, England. I've been a silent reader of this forum for a while now, and it seems to me this is the place to get some solid advice with my final project.

The brief I've set myself is

"Design an affordable and effective acoustic treatment solution for use predominantly in home studios and home recording scenarios."

I have a small amount of knowledge on the subject already, but I feel that in order to design and develop something really innovative and functional I should get some opinions from a range people more experienced than I am!

I would very much like to hear some peoples thoughts (positive and negative) on existing types acoustic treatment (please name no names!)

As I have aimed the product at the home studio market, it will be hard for it to cover all the areas commercial acoustic products can - which areas do you think would be most affective to focus the product on? (I.e. bass absorption, first point of reflection etc?)

This purpose of this project is to demonstrate my ability in the various design stages involved in developing a product from start to finish, and is in no way intended to be a commercial product or compete with any existing commercial products.

I only wish to take all of your opinions and advice into consideration to help me design a better product, not for you to do my project for me!

Thanks to those who took the time to read this, I look forward to hearing what people think!

Thanks
P
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2nd February 2010
Old 2nd February 2010
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Interesting subject.

Some layman's comments here.

The project is for the "design of an affordable and effective solution". In my understanding, the "solution" should be a combination of possibly different components used together as a system/solution.

Acoustic treatment is the application of the available tools-of-trade, mainly absorbtion and diffusion. Properly executed the solution works correctly.

The main issue in treating a room (be it a small listening room, a larger recording studio, a living room or a control room) is knowing what exactly to do. And as each room is different in size and layout, the exact same recipee might not be equally effective in different rooms. In some cases it might not even be applicable due to windows, closets, doors, etc.

One of the most common things discussed here is how to handle unique "features" of specific rooms.

IMHO, one can take the basic element of an absorber panel or a QRD diffuser as granted. The "recipee" for building a 2x4 absorber 4" thick is available and the results such an absorber will provide are relatively easy to calculate. The same applies to both 1D and 2D QRD diffusers. Certainly, designing an "affordable and effective" 2D skyline diffuser is an interesting task and many people here would love to see plans for such a thing. (Just check the threads on 2D diffuser builds to understand how much man-effort goes to the building of such a thing and how some small details can throw a build to failure).

So, having the basic treatment components available, the real step to go from problem to solution is knowing what component to hang where in the room and how to combine the required types of components in the correct proportions to solve the problem.

This is where room measurement comes in. "Unless you can measure something, your knowledge on it is primitive and just the beginning of a knowledge". Not my saying, I just quote this.

Once you have correct room measurements available, what you need is an algorithm that takes these measurements, process them and gives you a shopping list and a mouting plan as a result along with predicted measurements after treatment.

Sounds too complicated and sci-fi? It probably is but I am sure it is feasible. I recall the days when I was reading in prestigeus computer magazines how impossible it is to compress audio and images "as their entropy is pretty high and repetition is minimal". Well, 30 years later our audio and visual content rely on such impossible compression.

Actually, some of the steps required to establish the required components for treatment are widely used and pretty accurate. For example, if you measure the decay time of a room and also have a target value that suits the needs, it's pretty straightforward to calculate how many Sabins of absorbtion are needed and depending on material of choice, it's again pretty straightforward to calculate how much area must be treated.

Using the "best practice" experience that absorbtion must be distributed as much as possible, it's rather easy to produce a basic strategy for laying out the panels around the room. Combined with a schetchup program that allows you to define area available for panels and area reserved for other things, the task is simplified a bit.

Of course there is much more to it. How do you address that nasty peak of +15dB at 35Hz followed by a dip of -20dB at 40Hz?

Now, I would really love to see something like the nice QRD calculator giving answers to such questions, but I understand it's beyond the scope of a "final project". Probably in the scope of "an ultimate project".

But I've been interested in loudspeaker design since my childhood and in the late '70s loudspeaker design was mostly an art with some engineering knowledge emerging in the forms of papers describing algorithms for designing sealed and vented enclosures.

It's been already a few years where CAD software allows precice modelling of loudspeaker enclosure, crossover network, even baffle diffraction effects. Of course there's more to it but the existing tools already give one much better chances to build something close to what the design calls for.
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2nd February 2010
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Bass, bass and deep bass. Almost every home studio has 4 opposing walls and flat hard ceiling. This is a bass monitoring nightmare, creating room nulls and blooms.

First reflection stuff is mid/high and relatively easy to treat with the mirror on the wall trick (sit in listening position, have someone hold a small mirror on the wall to your left/right. wait till you can see you monitors in mirror, treat with some mid/hf absorption).

Bass is the real difficulty as the pressure waves are long it is difficult to design a product that will resonate in sympathy (convert sound to heat) and still leave room for the occupant. Typical control room bass traps have substantial air gaps (300mm and up) to allow the sound wave to be converted successfully.

I HIGHLY recommend you spend the next week reading here:

John Sayers' Recording Studio Design Forum • Index page

Then comeback with a sharper focus on what is involved with bass trapping in a small room.

Good Luck.
casual-p
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2nd February 2010
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Hi Sasi Sidi thanks a lot for your reply.
I tried to keep the brief as open and general as possible to give me the chance to explore all areas of room treatment and its various purposes!

So you would suggest definitely integrating the product with a room calculator?? I completely agree with you that measurement of the room and adjustment of the treatment is important. But to me this appears to be one of the major drawbacks of treating your room - although doing this will help to educate the person further and allow him or her to get better results from the resulting treatment, I feel that this could also deter people from treating their room with what it needs. Designing something that would make measuring the acoustic properties of a room easier and more accessible could be a very interesting avenue to go down!

Thanks also for pointing me in the direction of 2D diffusers, I'll try to do some reading into this.
casual-p
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2nd February 2010
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Hi Remo, thanks a lot for your comments.
I have been looking into achieving affective bass trapping with minimal air gaps and minimal thickness of material. It seems to me membrane traps appear to be some of the thinnest affective means of bass absorption? Something I would very much like focus some attention on is making the treatment consume as little space as possible in the room, or be easily removed and stored. This would help the product to be viable for those living in rented or student accomodation (I would love to treat my rented room but its size makes it completely impossible!)

Thanks also for the link to John Sayers' forum, I look forward to reading over some of the topics there.

I understand my questions may be a bit vague at the moment, I'm at the concept development stage at the moment! I'm basically just trying to figure out what is feasible so I can go on to sketch something a bit more technically detailed!

Thanks to everyone for their replies so far, I look forward to reading some more!

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2nd February 2010
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Lightbulb

Thanks for moving this to the public forum.

Quote:
Originally Posted by casual-p View Post
"Design an affordable and effective acoustic treatment solution for use predominantly in home studios and home recording scenarios."
Treatment strategies depend directly on the size of the room and an exact budget. Saying "affordable" means little because what's affordable to me may not be affordable to a 20 year old college student. But you seem to understand the basics very well:

* As much bass trapping as possible, in as many of the room's 12 corners as you can manage.

* Absorption at the side-wall and ceiling reflection points.

* Either more absorption or diffusion on the rear wall. Which you choose depends on budget and maybe also room size.

Pretty much everything you are asking is summarized in the short article:

Acoustic Basics

--Ethan
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2nd February 2010
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Quote:
Originally Posted by casual-p View Post
...
I have been looking into achieving affective bass trapping with minimal air gaps and minimal thickness of material. It seems to me membrane traps appear to be some of the thinnest affective means of bass absorption? Something I would very much like focus some attention on is making the treatment consume as little space as possible in the room, or be easily removed and stored. This would help the product to be viable for those living in rented or student accomodation...
In my first response I avoided commenting upon the properties of the actual "products" used to treat a room.

Before going into that, let me comment on
Quote:
So you would suggest definitely integrating the product with a room calculator?? I completely agree with you that measurement of the room and adjustment of the treatment is important. But to me this appears to be one of the major drawbacks of treating your room - although doing this will help to educate the person further and allow him or her to get better results from the resulting treatment, I feel that this could also deter people from treating their room with what it needs. Designing something that would make measuring the acoustic properties of a room easier and more accessible could be a very interesting avenue to go down
If we "study" the word "treatment" a bit, and use it in the same way medical doctors do, one cannot decide on a treatment unless a diagnosis was made. Most people visiting a doctor are sick, that we can take for granted, but the symptoms and sickness are usually different. So a medical doctor would be doing more harm employing the same treatment to all the patients.

One needs to really accept that each room is different. That makes the treatment a unique excercise that becomes easier provided experience, knowledge and tools.

Going on to the "cure", there are several options available on how to implement acoustic treatment.
I would recommend Cox & D'Antonio book on Diffusers and Absorbers as well as the Master Handbook on Acoustics by Alton Everet.

Some of the products designed and marketed are easy to purchase and mount. Like foam pads. That's why many rooms/home studios have foam on the walls although it is the cure for a problem they may not have. But foam looks nice and is lightweight and easy to apply. And if expensive it creates the expectation it is also effective.

To the other extreme is a skyline diffuser tuned to low frequencies. That can be a monster in dimensions.

Then there are hybrid solutions that combine absorbtion with diffusion and are lightweight, thin and modular. Something like acoustic tiles for the false ceiling. These are more geared towards portability and ease of use. There are not many such products available and - as you asked - I'm not mentioning any. Read the books.

Broadband absorber panels of the 2x4 variety can be considered as general purpose panels that are easy to use and mount and can never cause harm. They are the aspirin of the acoustician in a way.

Diffusers in general are difficult to make with 2D models much more complex than the 1D. However, a design that allows a diffuser to be distributed in kit form would be an interesting proposition.

In general, a small to medium home room (up to 30~40sqm) needs broadband absorbtion much more than anything else - disclaimer: taking into account that not every room is sick in the same way.

So, the product mostly interesting for the scope of your project would be a small, modular and easy to mount absorbing panel. Most rooms would also need corner traps but most spouses would freak at their sight. So another interesting quest would be a more wife-friendly solution to this problem, using the same modular components.
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2nd February 2010
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@Ethan:

I see what you mean about "affordable." I should have mentioned that I am aiming the product to retail at roughly between 300 and 500 USD, I think that should make it a bit more approachable to amateur musicians and producers. Thanks also for the link, I had actually been looking at some of the pages on your site and they have been really helpful!

@SaSi_SiDi

Thanks for the book suggestions, it turns out I coincidentally bought those two books last week (my poor wallet!) I see what you mean about rooms having their individual problems - this makes it pretty difficult to make a "1 size fits all" solution to room acoustics! Considering this though I think it could be really nice to develop a modular system that is really easy to tailor to the individual's room for the best results. Going a bit further with that I suppose it could be attractive to have a modular diffuser kit? I hope I'm right in presuming that the QRD diffusers have varying designs, it could be nice to experiment with a variety of the "templates" I've seen in various designs to decide which is best for the room.

Broadband absorption and bass trapping seems to be a nice starting point for the time being - I'll have to do some more detailed research into what's feasible for the brief and also my design abilities!

Thanks so much for everyone's help so far, I'm sure I'll pester everyone very soon with some more semi-layman's questions!
P

Last edited by casual-p; 2nd February 2010 at 05:05 PM.. Reason: stupidity
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3rd February 2010
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[Hey, what happened to the post I wrote here this morning ?]

Quote:
Originally Posted by remo View Post
Bass, bass and deep bass. Almost every home studio has 4 opposing walls and flat hard ceiling. This is a bass monitoring nightmare, creating room nulls and blooms.
I'm with remo. casual-p, if you could design a Helmhotlz resonator that was
adjustable and performant, perhaps in several different sizes, you would fill
a void in the currently available products. If you went all the way you could
sell them and pay for your studies, perhaps even finance a career on a beach
somewhere.

Might be tricky to come up with the product but if you did you would have
no problems selling it, people would come knocking at your door.

Do we get a copy of your paper ?

Paul P
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3rd February 2010
Old 3rd February 2010
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Hi paulp!
It's interesting to hear that there's such a void in the market, so it should be really useful to do some more reading and experiments with resonators! I'm currently trying to find somewhere in London where I can test some composites that haven't been used for acoustics before so it could be good to incorporate them into a Helmholtz resonator!

And of course to those who are interested, I'll try to keep this thread updated with sketches and CAD renders as I make them!

Thanks
P
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3rd February 2010
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A modular, tunable helmholz absorber a'la lego style would be a cool idea.
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3rd February 2010
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I've had a look at the Master Handbook of Acoustics and Acoustic Absorbers and Diffusers alongside some pages on the net, I can't seem to find any reasonably detailed plans for a simple resonator?? I have the facilities at uni to make accurate prototypes and would love to test them out.

My Acoustic Absorbers and Diffusers book suggests that Helmholtz resolator can be combined with Schroeder diffusers - this looks like a possible avenue to go down as it seems that a lot is happening in a small space! I was wondering whether anybody has any knowledge or has heard of diffuser/resonator combination in action?

Thanks
P
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3rd February 2010
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Quote:
Originally Posted by casual-p View Post
I've had a look at the Master Handbook of Acoustics and Acoustic Absorbers and Diffusers alongside some pages on the net, I can't seem to find any reasonably detailed plans for a simple resonator?? I have the facilities at uni to make accurate prototypes and would love to test them out.

My Acoustic Absorbers and Diffusers book suggests that Helmholtz resolator can be combined with Schroeder diffusers - this looks like a possible avenue to go down as it seems that a lot is happening in a small space! I was wondering whether anybody has any knowledge or has heard of diffuser/resonator combination in action?

Thanks
P
In modular formats, yes. I think there is a Swedish company that makes nice birch diffusers and HH absorbers that you stack. I've not really seen anything like that here in the US.
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3rd February 2010
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Quote:
Originally Posted by casual-p View Post
I've had a look at the Master Handbook of Acoustics and Acoustic Absorbers and Diffusers alongside some pages on the net, I can't seem to find any reasonably detailed plans for a simple resonator??
...and you probably won't find any. Crazy, but true. Partly that's because they're customized to every space, so it's hard to put anything general out there.

Frank
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3rd February 2010
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Quote:
Originally Posted by casual-p View Post
I've had a look at the Master Handbook of Acoustics and Acoustic Absorbers and Diffusers alongside some pages on the net, I can't seem to find any reasonably detailed plans for a simple resonator??
That's your job .

Quote:
I have the facilities at uni to make accurate prototypes and would love to test them out.
You would be doing the world a great favour.

Quote:
My Acoustic Absorbers and Diffusers book suggests that Helmholtz resolator can be combined with Schroeder diffusers - this looks like a possible avenue to go down as it seems that a lot is happening in a small space! I was wondering whether anybody has any knowledge or has heard of diffuser/resonator combination in action?
Interesting. The book proposes to use slats with 1D QRD profiles in a
Helmholtz slot resonator. Here is most of the chapter on resonant
absorbers out of the book : Resonant Absorbers. Both membrane
and Helmholtz absorbers are discussed.

Your mission, should you chose to accept it, would be to make something
that is adjustable, something that could be installed and then tuned to
the frequencies and bandwidth needed for the particular installation.

I'm not at all convinced that such a product can be produced, the most
compelling evidence supporting that is the dearth of commercial products.

Paul P
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4th February 2010
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@LonelyRaven

Cheers for that, I'm interested to see how the Swedish ones have been made modular (Probably extremely well knowing the Swedes!!) Quite reassuring that there is a niche in the US market at least for something like this!

@Weasel9992

I'm quite suprised that there are no basic plans around! The information that I've been able to find on the web seems to point to a few projects involving PCV pipe or something similar (with lots of debate whether they are effective or not) which is a bit challenging as I'm sure I'll have to do a lot more thinking to come up with one of my own!

@PaulP

Thanks for the mission briefing! I'm really glad that you mentioned ease if installation, adjustability and "tuneability" - from my limited experience and research these aspects seem to be some of the main contributors in preventing low-budget home studios from being treated for the problems specific to that room.

I think the main problem I'm going to run into is having to compromise on the capabilities of the product I'm designing - I understand that I can't design some variety of panel that treats all of a room's ailments! I feel that if I focus on some of the reoccuring and common problems, the areas I do focus on will achieve better results acoustically.

It might well be that I have to steer the design towards an affordable, innovative and adjustable product that can be easily used in conjunction with other products or DIY treatment, whilst reducing the need for them.


I've got a meeting with an Architectural Professor specialising in acoustics tomorrow morning, I'll post anything interesting that arises! Could be really useful to approach it from a different angle.

Thanks again for everybody's contributions!

P
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4th February 2010
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Quote:
Originally Posted by Lonely Raven View Post
In modular formats, yes. I think there is a Swedish company that makes nice birch diffusers and HH absorbers that you stack. I've not really seen anything like that here in the US.
Well, what do you know... Svanå Environmental Engineering.

Doesn't say how it behaves other that it's good below 100hz. I wonder how
precise the tuning is.

Paul P
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4th February 2010
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Quote:
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Well, what do you know... Svanå Environmental Engineering.

Doesn't say how it behaves other that it's good below 100hz. I wonder how
precise the tuning is.

Paul P
Here is the original page:

SMT AB

Some really nice photos in there...I really like the theater shot as it's sorta what I'm working towards in my home theater. Sorry I didn't share the link sooner, I was at work and didn't have it handy (and obviously didn't remember it was diffusor.com! LOL)
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5th February 2010
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Thanks for the links!
Just need to polish up on my Swedish! Some interesting looking products there, very nice build quality. Everything seems to look really heavy though! The "Golden Horn" caught my attention (Golden horn) - claims to diffuse 800-16000 Hz - would this range of diffusion be too broad for for treating rooms with small volumes?

Last edited by casual-p; 5th February 2010 at 07:25 PM.. Reason: lack of sleep!
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I wonder that to.
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