Measuring Sound
Design Strategy
How Many Decibels?
100

The rating that indicates the transmission of sound through construction materials.

What is STC (sound transmission class)?

100

When sound is reflected from a surface and scattered evenly back into the room.

What is diffusion?

100

The threshold of human hearing.

What is 0 decibels?
200

The measurement of sound level.  A measurement of 0 is the threshold of human hearing.

What is a decibel?

200

The blocking of sound transmission through a space or between rooms.

What is attenuation?

200

A whisper is approximately this many decibels.

What is 20 decibels?

300

A measurement of the amount of sound energy absorbed upon striking a particular surface.

What is NRC (noise reduction coefficient)?

300

The process by which a material,  or object takes in sound energy when sound waves are encountered (as opposed to reflecting the energy).

What is absorption?

300

A normal conversation is about this many decibels.

What is 40 decibels?

400

Ratio of sound intensity absorbed by the material to the total intensity reaching the material.

What is the coefficient of absorption?

400

The prolongation of sound as it repeatedly bounces off hard surfaces.

What is reverberation?

400

A noisy restaurant or a hairdryer is about this many decibels.

What is 70 decibels?

500

The amount of sound lost through a partition.

What is transmission loss?

500

The two important qualities of a partition to impact with transmission of sound.

What are mass and stiffness / rigidity?
500

A jet plane taking off is about this many decibels.

What is 120 decibels?

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