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Acoustical Properties
Effectiveness in sound control is an important quality in insulation, and T·A·P performs well acoustically. We naturally think of insulation affecting noise outside the envelope of the building, such as traffic, lawnmowers, and barking dogs. But more and more, consumers wish to insulate interior walls to reduce unwanted noises such as appliances, entertainment systems, and bathroom sounds.

A laboratory rating dubbed Sound Transmission Class (STC) is used to measure sound-deadening ability, The higher the STC number, the more sound is diminishedi. (see chart).

 

STC Rating Description of Performance
30 Loud speech understood fairly well
35 Loud speech audible but unintelligible
42 Loud speech audible as a murmur
45 Must strain to hear loud speech
48 Some loud speech barely audible
50 Loud speech not audible

Both Owens-Corning and the Cellulose Insulation Manufacturers Association have tested their products for STC ratings. The insulations were installed in walls, and tested with an empty wall as a reference. An empty wall does impede some sound travel, and achieves a rating of 35. Owens-Corning reports that their fiberglass insulation achieves an STC rating of 39 . Cellulose is commonly listed with an STC 44 .

The major reasons for the difference in STC rating are the physical attributes of the two products: density and texture. Denser cellulose, a wood-based product, disrupts and scatters sound waves, so that less noise can pass through it.

But it should be noted that STC ratings are tested in a laboratory setting that does not always mimic the conditions of real houses. STC ratings are also listed with perfectly-installed insulation. But gaps and voids associated with installing fiberglass create a conduit for sound waves to skirt the insulated portions of the wall and transmit sound into the room. Since blown-in T·A·P, with its dense, form-fit, allows no such gaps or voids, acoustical performance improves, and rooms are quieter. T·A·P’s excellent acoustical performance may be an unexpected bonus for the consumer.
i "T·A·P Pest Control Insulation: Specifications." Charlotte: T·A·P Insulation, 2001.
"Noise Control Design Guide." Owens-Corning Fiberglass Corporation.
Cellulose Insulation Manufacturers Association.
 
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