| | WELCOME TO OUR MONTHLY NEWSLETTER | We plan to keep our newsletter short and to the point, presenting news, articles,
and facts you’ll find interesting, informative and even entertaining. |
| | Dave Adams and Stephanie Adams-Ball attended a meeting of the National Council of Acoustical Consultants the latter part of May. D. L. Adams Associates has been a member of NCAC for more than 30 years. Stephanie currently serves on the Board of Directors of NCAC and has taken on revamping NCAC’s website–a task she is hoping to complete in the near future. Dave, a past president of NCAC, currently serves on the organization’s Long Range Planning Committee.
The NCAC meeting preceded the Acoustical Society of America's 161st meeting which was also held in Seattle, WA. Dave stayed on for the ASA meeting and chaired a paper session, Developments in Plumbing Noise, which was jointly sponsored by two of ASA’s technical committees, Architectural Acoustics and Noise.
In addition to NCAC’s general membership meeting and exhibits of acoustical materials and products by 20+ manufacturers, NCAC members had the opportunity to attend an opera, The Magic Flute, Saturday evening at Seattle’s Marion Oliver McCaw Hall, home of the Seattle Opera. The highlight of the NCAC meeting was a visit to an abandoned nuclear power plant near Elma, WA, which is now the home of NWAA Labs, an independent acoustical testing facility. |
| | | Photo of NWAA Labs. The labs occupy an abandoned nuclear power plant near Elma, WA. |
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| | | | Dave Schram recently returned from InfoComm in Las Vegas armed with information and data on the latest technology, equipment and components in the AV and IT fields. |
| | Dave Manley recently completed a one-month tour-of-duty in Hawaii assisting our Kailua engineers. |
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| | | | | Jeff Kwolkoski co-chaired a paper session with Jeff Babich at the Institute for Noise Control Engineering (INCE) meeting in Portland, OR in July. The subject of his session was Unconventional Construction Methods and Materials. |
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| Tips for Architects: Rooms with Projectors | Position Square to Screen
When a projector is located off-axis to the screen, keystone correction and lens offset is needed to fit the image to the screen. The projector is actually scaling and processing the image. Use of this feature reduces the number of pixels on screen, diminishes the quality of the image and costs more. Pick a position for the projector that is square to the projection screen.
Overcoming Ambient Light
Ambient light in the room and more specifically the ambient light that falls onto the screen will wash out the picture and reduce the contrast. Contrast is the element that gives us depth of field and the appearance of increased resolution. Room lighting near the screen should be separately controlled. Position the projection screen to keep ambient light off the viewing surface.
Keep the projector close to the screen
The distance of the projector from the screen directly affects image brightness. Brightness will decrease by a square function as the projector is moved further away from the screen. Moving a projector back from 10 to 20 feet will cut image |
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| brightness by up to 75%, depending on the quality and design of the lens optics. Position the projector as close as possible to the screen to maintain brightness.
Avoid Zoom Lenses
If you can’t position the projector near the screen, it could require the use of a zoom lens to fit the image to the screen. Zoom lenses reduce the light output. Most if not all manufacturers provide a chart of projector distances to the screen for their standard fixed lens. Locate the projector at a distance where a fixed lens can be used.
Keep Task lighting levels low
While task lighting in classrooms, meeting rooms, lecture halls, etc., is important to allow the audience to take notes, it directly competes with projected images. If there is a great deal of task lighting, it will cause the iris of the eye to close down when the viewer looks at the images on the screen. To correct this, a projector with more light output, i.e., a more expensive projector, will be needed. Keep task lighting levels as low as practical.
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| | : A Story from Mick Barnhardt |
| | Resilient channels are an acoustical innovation that have been around for a long time–at least since 1979 when I started here with my newly earned engineering degree. It is a simple idea, using a thin, 25-gauge, piece of metal fabricated such that drywall can be installed on a wall stud or ceiling joist and the only connection between the stud or joist and the drywall is the metal channels. These channels can provide a significant improvement in the wall or floor-ceiling assembly’s Sound Transmission Class (STC). An improvement of as much as seven points. This improvement stands up in theory and in lab tests, but in the field it could fall short due to improper installation. A common fix we run into is where |
| someone attempts to improve the sound transmission loss of, say, an existing wall by installing the resilient channels over the surface of the existing drywall and then adding another layer of drywall on the resilient channel. Essentially, they sandwich the resilient channel between the two layers of drywall. Well, they soon discover, they don’t work this way and this improper use will result in a wall that performs, acoustically, worse than the original wall.
Another common mistake is the use of drywall screws that are too long. Excessively long screws used to attach the drywall to the resilient channel could result in shorting out the resilient channel if they penetrate far enough to catch the studs or joists. In so doing, the performance of the resilient channels is degraded. It is important to use the proper length of screw for the thickness of drywall you are using. |
| | New Projects | We have been selected to provide consulting and design services (acoustics, theatre, AV and IT/Communications) for the New Ute Theatre project in Rifle, CO. This project involves the remodel of the Rifle Creek Theater, resulting in a downtown, centrally-located, multi-purpose event venue.
Another new project is a noise and vibration impact assessment study for a proposed development near Kawaihae Harbor on the Big Island.
We have just been selected to provide recommendations for improving the acoustics in one music room in the Music Building and three auditoriums–two in the Marine Science Building and one in the Physical Science Building on the University of Hawaii at Manoa campus.
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