| | 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. |
| | We have extensive experience in designing AV, low-voltage and structured cabling systems for school, hospitals, lab facilities, etc.? |
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| | | DLAA 2011 Cookbook:
We are so excited for our 2011 Cookbook! This year, we assembled a creative team (all DLAA employees!) to come up with our best Cookbook so far. If you would like to be added to our mailing list, and receive a copy of our special New Year's themed cookbook this year, please let us know.
Special thanks to Andrew and his photography skills, Stef's talent in the kitchen, David Manley assisting, Mick's beautiful home, and Jessica's set designing and arranging. |
| Tips for Architects and Contractors | : Acoustics for Large Classrooms |
| Large classrooms that utilize audio and video equipment geared for presentations have become more and more common in all types of schools in recent years. These types of spaces can be a great place to incorporate some natural acoustical features into the architectural design to complement the systems within. Below are some design tips to consider when working with these types of spaces.
• Dedicated “front” and “rear” sides of a room are often required to make the maximum use of natural acoustics.
• A sloped floor can help improve sight lines for students to see presenters more easily, and in addition, improving the direct sound to the students near the back of the room which will allow them to hear presentations more clearly.
• Parallel side walls can often result in “flutter echo” which may require acoustical wall panels to treat. Splaying the side walls by, at minimum, 5 degrees can help | |
| limit this acoustical effect (#1 in the figure to the right). In general, it is highly beneficial to the sight lines and acoustics for the side walls to be splayed such that the room gets wider towards the back.
• Video projectors and/or LCD screens are a common focus point for presentations. To assist the audience in viewing them when multiple off-axis displays are used (#2 in the figure to the right), it can sometimes be helpful to splay the front walls inward by 5 degrees as well to improve audience sight lines to the screens.
• The rear wall is a common source of unwanted and distracting reflections in this type of room, and a common surface to plan for acoustical treatment. Acoustical treatment can be hidden behind many types of surfaces including wood grilles, perforated metal, stretched fabric, and many other options that can blend well with nearly any architectural design when planned for ahead of time. |
| | | During an extensive noise measurement study on the rugged and seldom visited lava fields on the east coast of the Big Island of Hawaii, a strange acoustical enigma was solved, but only after several intense moments. First, I would like to set the stage. Leaving the main, North-South highway on the East side of the Big Island, Mamalahoa Highway, near the town of Pahala, we took our 4WD vehicles and our noise source eastward, toward the coast. The dirt road ended after about a mile at the edge of a macadamia nut farm. From there, it was a grueling, tooth-jarring ride through tall grass, topical flora and black, craggy, lava fields before we reached the coast. Five of us–me, a Harley Davidson owner and his wife with his straight-piped chopper–our noise source–and two U.S. Navy meteorology experts, set up camp near the shore.
Our mission was to document a condition known as sound refraction, a phenomenon that occurs when sound waves, which normally propagate outward in an expanding sphere pattern, are bent or channeled back to earth due to a temperature inversion. This results in a condition where sound levels at large |
| distances from the sound source can be 15 to 20 decibels higher than that expected due to normal sound attenuation with distance. We suspected this situation would occur at that location because of where it was with respect to Mauna Kea, the highest mountain on the Big Island. During the night, cold air slides down the slopes of the Mauna Kea and nestles itself beneath the warm air caused by the sun heating the lava fields and the warm trade winds off the ocean.
Twice during the night (that is, at midnight and at 2:00 A.M.) for five nights, the Navy personnel launched weather balloons that transmitted wind and temperature gradients as a function of altitude back to ground while the sound source, the straight-piped Harley, was rived at a high rpm, producing the maximum noise level it was capable of producing. I was measuring at a distance of 50 feet from the exhaust and coordinating the efforts of all involved. Four other observers with sound level meters were positioned in a line at one-half mile, one mile, two miles and three miles from the source.
We found and documented sound refraction and we were able to relate it to the temperature inversion; however, there was another discovery made. In the middle of one night between noise tests a strange and eerie noise was heard by all–a periodic clicking sound followed by a few seconds of silence and then again click, click, click, click. Via our walkie-talkies, I asked the four observers if they had heard the clicking sound in the hope of identifying its source. All but one replied, yes, they had heard it, but none could tell where it was coming from. Finally, the last observer replied in a sheepish voice, “Oops, I didn’t think anyone would hear it. Can anyone tell me how to crack a macadamia nut? I was banging this macadamia nut between two rocks, but these darn things have to have the hardest shell in the world.”
The mystery was solved. And, the rest of us agreed that without doubt macadamia nuts have the hardest shell in the world. Then, we harshly admonished him for interrupting the testing in an attempt to have a late night snack and we advised him that the easiest way to eat macadamia nuts is to buy them already shelled from the store. It would certainly be much quieter. |
| | New Projects | Regis High School Performing Arts Center
Lodge on Biltmore Estate
Kittredge Central & West
| Completed Projects | Frederick High School
Red Hawk Elementary School
Colorado School of Mines Brown Hall
Center PK-12 School LEED
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