|
A decibel (dB) is the unit of measurement for sound intensity. Broadly, there are two types of sounds within a building: (i) Airborne Sounds, which are sounds transmitted though air, such as voices or radio playing, and (ii) Impact Sounds,
which are created by an impact of an object with building elements or
furnishings, such as footsteps, dropped objects, toys, furniture
scraps, piping, and some appliance sounds.
|
| |
|
A 10 decibel increase means the sound is ten times louder. Prolonged
exposure to noise louder than 85 decibels can impair hearing.
|
|
| |
Very painful |
160 |
Shotgun |
|
| |
Painful |
140 |
Stock car race |
|
| |
|
130 |
Jackhammer |
|
| |
Deafening |
120 |
Rock concert |
|
| |
|
100 |
Chainsaw |
|
| |
Very loud |
90 |
Hair dryer |
|
| |
|
80 |
Police whistle |
|
| |
Loud |
70 |
Average radio |
|
| |
|
60 |
Normal conversation |
|
| |
Moderate |
50 |
Average Office |
|
| |
|
40 |
Quiet radio |
|
| |
Faint |
30 |
Whisper |
|
| |
|
20 |
Rustling leaves |
|
| |
Very faint |
10 |
Soundproof room |
|
| |
|
0 |
|
|
| |
| STC: |
|
Sound Transmission Class.
A laboratory measurement of the ability of walls and floors to mitigate
airborne sounds including voice, television and alarm clocks. |
| |
|
|
| NIC: |
|
Noise Isolation Class.
An over-all measure of the sound isolation between units in a
multi-family dwelling. A field measurement of the ability floor/ceiling
assembly to mitigate airborne sounds. |
| |
|
|
| IIC: |
|
Impact Insulation Class. A laboratory measurement of the ability of proposed materials to mitigate against impact sounds such as footfalls. |
| |
|
|
| FIIC: |
|
Field Impact Insulation Class.
A field measurement, i.e., done after a hardwood floor installation is
completed to test actual noise transmission into the unit below. |
The higher the value, the greater the noise isolation. For example, an
STC of 52 provides better sound protection than an STC of 45. Building
codes typically require that floors provide an airborne sound
insulation to meet an STC of 45 (field-tested) and an IIC of 45 (field
tested) for impact noise. Note: local building codes may require higher standards. |
RECOMMENDATION: Boards should establish
noise standards for the installation of hard-surfaced flooring.