Acoustics, Noise & Vibration Control Sound Isolation Partitions provide a certain level of privacy or sound isolation between two spaces, depending on their assembly. Each partition has a sound transmission class (STC) rating, which indicates its laboratory-tested performance.
STC Rating
Subjective Evaluation of STC Rating
30
Normal speech can be understood fairly well.
35
Loud speech intelligible.
40
Onset of “privacy.”
45
Loud speech audible and occasionally intelligible.
50
Normal speech levels not noticeable (NBCC/OBC for residential demising walls).
55
Highly raised speech levels occasionally noticeable but unintelligible.
60
Most sounds are inaudible.
Of note, a partition will typically have an apparent STC (ASTC) 3 to 5 points lower than its laboratory-tested STC when measured in the field. This is due to the influence of flanking paths and imperfections in the construction of the partition.
Room Acoustics
Background Sound Levels
Reverberation time is the length of time it takes for a sound to decay 60 dB.
Noise criteria (NC) ratings are used to specify maximum background sound levels.
Mid-Frequency Reverberation Time (sec)
3.0
Churches
Room Type
NC Level
Concert halls & recording studios.
< NC-20
Theaters, chapels & large meeting rooms.
20 to 30
Bedrooms, hospitals & hotels.
25 to 35
Private offices, classrooms & libraries.
30 to 35
Retail shops, restaurants & gymnasiums.
35 to 40
Lobbies, laboratories & maintenance shops.
40 to 45
Kitchens & industrial shops.
45 to 55
Concert Halls
2.0
1.4
Cinemas
Studio (Music)
1.0
Standard Offices
Studio (Speech) 0
50
100
Television Studios Burolandschaft Offices
Conference Rooms & Lecture Theaters 500 1000
5000 10000
Room Volume (m ) 3
Thornton Tomasetti applies engineering principles to solve the world’s challenges – starting with yours.
www.ThorntonTomasetti.com
Acoustics, Noise & Vibration Control Floor Systems & Vibration Criteria Vibration Criteria
Description of Use
Perceptible vibration. Appropriate to offices and non-sensitive areas.
Residential Day (ISO) (200 μm/s)
Barely perceptible vibration. Maximum recommended for general sleep areas. Usually adequate for computer equipment.
Residential Night (ISO) (140 μm/s)
Appropriate for most sleep areas such as hospital recovery rooms.
Operating Theatre (ISO) (100 μm/s)
THRESHOLD OF PERCEPTIBLE VIBRATION. Suitable in most instances for surgical suites, catheterization procedures, and for other equipment of low sensitivity. Suitable for very sensitive sleep areas.
VC-A (50 μm/s)
Adequate in most instances for microbalances and optical balances. Also suitable for most vivaria.
VC-B (25 μm/s)
Micro-surgery, eye surgery and neurosurgery, CT, CAT, PET, fMRI, SPECT, DOT, EROS.
VC-C (12.5 μm/s)
Appropriate for many MRIs, NMRs, and moderately sensitive electron microscopes to 1 μm detail size.
VC-D (6.25 μm/s)
Suitable in most instances for demanding equipment, many MRIs, electron microscopes (SEMs and TEMs) to 0.3 μm, and E-Beam systems.
VC-E (3.12 μm/s)
A challenging criterion to achieve. Assumed to be adequate for the most demanding of sensitive systems, including long-path, laser-based and small-target systems; those working at nanometer scales; and other systems requiring extraordinary dynamic stability.
VC-F (1.56 μm/s)
Appropriate for extremely quiet research spaces. Generally difficult to achieve in most instances. Not recommended for use as a design criterion, only for evaluation.
VC-G (0.78 μm/s)
Appropriate for extremely quiet research spaces. Generally difficult to achieve in most instances. Not recommended for use as a design criterion, only for evaluation.
Concrete
Office (ISO) (400 μm/s)
Slab on Grade
Distinctly perceptible vibration. Appropriate to workshops and non-sensitive areas.
Steel Composite
Workshop (ISO) (800 μm/s)
Recommended Floor Construction
Thornton Tomasetti applies engineering principles to solve the world’s challenges – starting with yours.
www.ThorntonTomasetti.com