Page 24 - Modernfold Architectural Products

Acoustical Guide
Operable Partitions

Field Sound Tests (NIC& FSTC) been properly installed, is operating properly, and
The field performance of a building’s operable to discover any significant flanking paths (which are
wall is covered by ASTM E-336. Field test results are typically not within the control of the operable wall
calculated according to ASTM E-413 and reported as installer and manufacturer).
Noise Isolation Class (NIC) or Field Sound Transmission
Class (FSTC). It should be noted that NIC ratings Sound Absorption
are determined using Noise Reduction (NR) data, All building materials provide some sound absorption,
the arithmetic difference between sound levels in but only those materials that have relatively high
the sending and receiving rooms. NIC ratings are sound-absorbing properties are useful in reducing
dependent upon the amount of sound-absorbing sound levels within a room and in improving room
material in the receiving room and the size of the acoustics for many room uses. Sound-absorbing
operable wall. properties for a particular material are expressed by
the material’s coefficients of absorption (which vary
FSTC ratings attempt to remove the effect of receiving with frequency). A common one-number rating for
room sound absorption and the size of the particular sound absorption is the Noise Reduction Coefficient
partition. FSTC ratings are the field version of labor­ (NRC), the average of coefficients of absorption
atory STC ratings. Experience indicates that NIC ratings at frequencies from 250 Hz to 2000 Hz. In general,
will be approximately 9 points lower than carefully soft porous materials have high NRC ratings when
controlled laboratory STC measurements for any compared with hard materials such as gypsum
particular operable partition type. FSTC ratings can board, plaster, or concrete. Effective sound-absorbing
be higher or lower than NIC ratings depending on the materials will have an NRC rating of 0.65 or greater.
relationship between the size of the partition and the So adding porous materials such as sound-absorbing
amount of sound absorption in the receiving room. ceiling and wall materials, drapery, upholstered
furniture, and carpet can increase both the comfort
Assuming that the proper partition type has been and acoustic performance of a facility. In regard
selected for a particular application and that the to operable walls, NRC ratings apply only to the
partition is properly fabricated, the purpose of field performance of sound-absorbing panel faces.
measurements is to show that the partition has

Sound Advice
• Acoustical control is critical in most facilities and it’s a sound investment worth making.
• Wall systems are ranked according to Sound Transmission Class (STC) Ratings.
• Ceilings, floors, and furnishings are important to acoustic control.
• Flanking paths can significantly diminish the sound­reducing properties of an installed operable wall, but
they can be avoided with proper building design and barrier installation.
• Remember, the sound­reducing properties specified for the operable partition must be matched by the
surrounding ceiling, walls, and floor—the acoustical envelope.

215 West New Road
Greenfield, IN 46140

Tel: 800.869.9685

Email: info@modernfold.com
Website: www.modernfold.com

Form No. 2503 04/18