At a Glance: Acoustics, Noise & Vibration Control

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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

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