Acoustic Room Mode predictor

by Administrator 13. September 2006 03:41

If you know me, you know I am an audio nut.  A peak at my living room (pictured here) might give you an idea I'm not well in the head, let alone the lunacy involved in the custom home theater that's being built in the basement right now.

The world of audio is a great place to observe tons of Snake Oil being sold and a sad, sad departure from the available Science that could guide us towards better sound.  Its not unlike many areas of computer science, where the Morts have never even heard of the science their day-to-day work is based on.  If you know SQL experts who are great at their job but who weren't aware that the concepts come from relational algebra, set theory, etc. then you know what I mean.

Over the past year I've become very interested in the effect the listening room has on sound.  Audiophiles like me spend a fortune on equipment that has perfect frequency response and near-zero harmonic distortion then put the system in a room that creates 30db peaks and valleys and flutter echos that ruin the stereo image, the list of room problems goes on and on.

I recently created a Room Mode calculator for my audio site, http://www.KlipschCorner.com/.  Room Modes are essentially the frequencies your room will cause to sound louder than they should due to the dimensions of the room.  For example, a 60hz sound wave is 19 feet long making a room with any dimension being 19feet a bad call.  Rooms with the common 8ft ceiling are tough to treat due to the frequency ranges being close to 8ft or 4ft.  A room mode calculator is useful when planning a new listening room because one can quickly see if there will be room modes at any "problem" frequencies and also see the distribution of room modes, where an even distribution is desirable.

There is a graphical component as well as a tabular component.  My hosting provider, while their service is great, chose to license a rather poor charting utility, so if anyone wants to send a free license of Infragistics my way you'd be saving me a lot of pain.

You can see the end results at http://www.KlipschCorner.com/Tools/ModeCalc.aspx and I suppose I can make the KlipschCorner.Acoustics library as it stands now available via some open source license.

I wonder if DirectSound could be made to do some time-domain analysis (using test tones and a microphone for input) for calculating sound decay rates vs ambient noise in a room?

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Been Busy

by Administrator 13. September 2006 03:27

Its not like me to not blog like this, man have I been busy.  Its time for an update.

My new title is Director of Mobile Technology at CarSpot.com here in Milwaukee.  My mandate is to create a .Net development department for Mobile, Web, and Desktop development, establish code guidelines, architectural guidelines, and best practices, try to get some best practices carried into the other technical departments, etc. 

So far I have re-architected and re-written one of our products, and am in the process of doing a 50-client release of this product.  Fifty units is a big deal on this product so I've had my hands full.

Generally, I'm hoping to have a better chance at "doing things right" than I've ever gotten as a consultant.  At a product company, where the product IS the focus, its easier to convince management to invest in getting the right tools and going back to refactor things and all that.  Contrast this to consulting where "Oh that damn web site project for FY07 planning" is always being pushed out far faster than is practical and quality of product and quality of life always suffers.

I have some long overdue technical stuff coming up next.

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About the author

Damon Payne is a Microsoft MVP specializing in Smart Client solution architecture. 

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