August 2014: Acoustical Sustainability

This month’s newsletter will discuss sustainable acoustical products. Most of us think of foams or mineral fiber as acoustical products; the use of biomaterials such as straw, hemp, flax, sheep wool, duck feathers and mushrooms are not our idea of garden variety products for acoustics. Read on to learn more about unconventional acoustical uses of some man-made and natural materials.

A material is considered sustainable if its production enables the resources from which it was made to continue to be available for future generations. Further, a sustainable product must be created repeatedly without generating negative environmental effects, causing waste products or pollution, or compromising the well-being of workers or communities. Recycling is generally considered a form of sustainability in part because the process contributes to lower waste production and reduced use of raw materials. Here are a few common products that can be reborn into acoustical materials:

Plastic bottles: Plastics used for bottled water are recycled and processed into polyester fiber. When layered and needled into 5/8″, 1″ or 2″ panels, they produce excellent sound absorption and are naturally fire proof. Installed on walls of public spaces such as schools they offer results superior to any wall covering. Plastic water bottles had an expected life cycle of less than 6 months then off to a landfill, but now they can be soaking up noise for 30 to 60 years!


Jeans: A wardrobe staple since 1873, jean manufacturers today send their remnants to be used for interiors of cars, trucks, buses, trains, planes and classroom wall panels.  The felt, a cotton/polyester blend, is compressed and covered with vinyl for vehicles, but for classroom acoustics, the cotton felt is rolled into 1″ or 2″ sheets which are hung with clips and covered with frame tensioned fabrics.  They make great sound absorbers!


Tires: For years, piles of old tires grew like mountains on the landscape until recently when processes were developed to grind them into a granulate, then mixed with a binder to produce layers of material that offer a range of hardness values. These products are used as underlayments for floors to significantly improve impact sound transmission.


Hemp: For thousands of years, hemp has been used to produce clothes, paper, oil, and medications. Growing hemp naturally improves soil conditions and pesticides are not necessary. Used for thermal and acoustic insulation, hemp is a sustainable product that contains no additives that harm the environment or pose a health hazard.

Sheep wool panels at the Barnes Foundation.


Sheep wool: Sheep farms are all over the world. The quantity of potentially recoverable wool is estimated at 14,000 metric tons per year for the manufacture of thermal/acoustic insulation. The acoustical panels inside the Annenberg Court at the Barnes Foundation in Philadelphia were handcrafted in the Netherlands by a sheep farmer.

The use of natural materials for acoustical solutions provides an environmentally sound room and is environmentally sound!

September 2014: Let’s Get Weird
July 2014: Connecting the Dots