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