Noise Curtains

by dB Engineering

Quieting A Harbor Tunnel

Noise Curtains in a harbor tunnel
This section utilized (420) BBC-13-2" Acoustical Curtain Panel to significantly reduce construction noise...

This tunnel project is the largest highway construction job ever undertaken in the United a cost over $11 billion dollars! One sensitive issue of such a significant project is how construction noise will impact local businesses and residences. A unique, open-air collection of restaurants, shops and offices, is located adjacent to a section of the project requiring working underneath an overhead highway, while a densely populated residential area is located on the opposite side. Thus, the noise impact upon the markets and residences is even greater from the direct construction noise as well as the reflected noise off the deck.

It was determined that BBC-13-2" Acoustical Curtain Panels would offer the required noise reduction. BBC-13-2" Acoustical Curtain Panels are a combination of a 2" thick vinyl-faced Quilted Fiberglass Sound Absorber and a 1 lb PSF reinforced loaded vinyl noise barrier. Modular Panels are constructed with grommets for attaching to the framework as well as exterior grade hook and loop fasteners for joining adjacent panels together. Over 400 such panels are manufactured and shipped within a three week period. As the panels were being installed, preliminary sound level testing showed a 9 to 10 dB(A) reduction in noise levels even before the entire job site was buttoned up. This was just the kind of noise reduction promised to the local community.

Many other sections of the massive project have also utilized the Curtain Panels with even better results since they were not located below an overpass, with completed sections showing noise reductions up to 12 dB(A). A common treatment is to have the Curtains installed on fence posts inserted in pre-cast concrete highway barriers. This allows for the noise reduction treatment to be easily relocated along with the highway barriers.

BBC Panels in a tunnel

BBC industrial Noise Curtains in a construction site

BBC Panels are tough enough to be used at any job site.

In conjunction with the Noise Barrier/Sound Absorption Walls, a significant quantity of portable "Hoistable Curtain Enclosures" are manufactured. The BBC-13-2" Acoustical Curtain Panels are installed on heavy duty frames to drop-over jackhammer operations during that phase of construction. The jack-hammer operator works inside the three-sided roofed enclosure to screen that very loud operation from the neighbors. The enclosure is then lifted by crane and dropped onto the next section they are working on. By combining a sound absorber with a noise barrier at construction projects such as these, the Acoustical Curtain Panels offer noise reduction for construction workers as well as serving the primary purpose of keeping noise levels at a minimum in the neighborhood.

Sound Transmission Loss (dB) Octave Band Center Frequencies (Hz)

125 250 500 1000 2000 4000 STC
BBC-13-2" 13 20 29 40 50 55 32


Sound Absorption


Octave Band Center Frequencies (Hz)

125 250 500 1000 2000 4000 NRC
BBC-13-2" .07 .27 .96 1.13 1.08 .99 .85


Table showing how the human ear perceives noise reduction.

Decibel Reduction Reduction Experienced by Ear
2 15%
4 23%
6 38%
8 48%
10 56%
12 63%
14 68%
16 75%
18 77%
20 81%