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AudioAcoustics

Serving the Acoustics Community Since 1994

Cross-Spectrum Acoustics Inc. offers Sound & Vibration Consulting Services

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Mar 19, 2008

Dick Campbell posted this NYTimes article about classroom sound reinforcement systems to the NCAC listserve:

This school year, Wyoming Elementary has equipped every kindergarten through third-grade classroom with the amplification system, technology that was once reserved for large lecture halls or to aid students with hearing or learning disabilities. In an era of chronic ear infections, widespread iPod use and rampant attention-deficit disorders, school officials have embraced the microphones for mainstream classrooms, pointing to research suggesting that all children learn better when they hear instruction loud and clear.

Yes, it’s true that kids lean better when they can actually hear and understand the instructional material. But using a sound-amplification system is more of a band-aid than a solution. Proper acoustical design is much more effective and relatively inexpensive if considered during the classroom design/renovation process:

“I’m appalled. This is the triumph of marketing over science,” said David Lubman, a fellow of the Acoustical Society who lives in California. “In most cases, they’re putting it in as a substitute for good acoustics. In other words, instead of cutting down the noise, they’re blasting over the noise, so the net result is more noise.”

Some really smart people wrote an ANSI standard that specifies best-practices so you can get it right the first time.


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Mar 10, 2008

NTI has scheduled another FTA Noise & Vibration Impact Assessment course for March 18-20 in Oakland California. I won’t be helping out this time but Lance will treat you right.

FTA developed (and when I say “FTA developed” I mean “FTA paid NTI who paid HMMH who paid me to revamp”) a noise prediction spreadsheet for use in the general assessment phase of the noise analysis. FTA also has a general assessment procedure for rail that involves picking vibration levels for various sources off of plot in the FTA manual. When doing the course vibration exercises I found that I got slightly different answerers each time I worked a problem because I would pick a slightly different value from the plot. To make things easier on myself, I whipped up a small program that provides the reference vibration level for a specific source at a given distance and speed.

Of course I couldn’t just build a utility to pick plots off a plot… I spent a little extra time and built an advanced mode that you can use to predict vibration levels using the FTA general assessment procedure. The utility doesn’t provide guidance as to how to make predictions; I assume that anyone who uses this utility knows what they are doing. If you don’t, please don’t try to use this utility - spend some coin and hire a professional. There are some real good ones out there.

This utility is provided AS-IS without warranty of any kind. This utility has NOT been commissioned or endorsed by the Federal Transit Administration. Please direct all inquiries to me.

Download:     Mac Version    | Windows Version


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Man Fed Up With Construction Noise Brandishes Weapon:

A man who told sheriff’s deputies that he couldn’t sleep because of the backup beep of a truck at a nearby construction site is accused of brandishing what looked like a handgun at the workers.

I’ve heard a similar story while working as a noise-enforcement officer for a construction project. When responding to a noise complaint, the contractor supervisor came over to me and immediately offered to do everything in his power to address the noise complaint. As you might guess, it’s pretty unusual for any contractor to care about anything other than the immediate task at hand, so his responsiveness was welcome.

After we got everything worked out, the contractor revealed the reason for his concern - at a previous job, he and his crew had been threatened at gunpoint for making too much noise at night. As a wise man once said, “You can get much farther with a kind word and a gun than you can with a kind word alone.”


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Mar 05, 2008

Inside George Lucas’ Skywalker Ranch:

Walking through the Main House, with its inlaid brass, amber lights and honeyed glow, is to stroll through a stately past. It’s very different, though, at the busiest site on the ranch, the Technical Building, the sleek home of Skywalker Sound, a highly regarded brand in Hollywood postproduction. There, I watched digital artisans work in sound-effects studios, on a huge scoring stage and in mixing suites outfitted with state-of-the-art gear. Because the ranch has a pastoral, summer-camp setting, these workspaces make Skywalker a favored spot for filmmakers who yearn for Walden Pond but with the computer power of the Pentagon.

Lucky bastard. I need someone with connections to hook me up with a tour.


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