Hazardous Noise Control in Green Building

A Quiet, Green Home  

It is both as noise can be hazardous. Two factors determine this: 

• Intensity (Loudness) measured in dBA 
• Time of Exposure measured in hours and minutes.

The louder the noise, the more hazardous it is but the dBA level alone does not define noise hazard. The longer the exposure time, the more hazardous the noise. A “Noise Dose” combines both loudness and time and is a convenient way of describing the relative hazard of the noise.  "Noise Dose" defines the noise hazard.
Noise Dose = Loudness + Exposure Time
Quiet (45dBA) for 8 Hrs = 0% Noise Dose

One other point: Loudness is measured using a logarithmic scale. This means that a 10 decibel increase does not simply add 10 to the previous level. It multiplies the previous level by 10.

Examples:

Quiet room: 45 dBA
Conversation: 55 dBA = 45 dBA x 10
Car (50 mph at 50 ft)  65 dBA = 45 dBA x 100

Noise that is louder than busy city traffic for any length of time is potentially hazardous.

Perception

1 or 2 dBA are not perceptible to most humans outside of a carefully controlled lab environment. A change of 3 dBA is discernible, however, and a change of 5 dBA is clearly discernible. That is the dBA change from a quiet room to a conversation.

With respect to a reference sound level, a change of -5 dBA is perceived by the human ear as ¾ as loud; a change of –10 dBA is perceived as 1/2 as loud; and a change of –20 dB is perceived as ¼ as loud. 

Distance is also important to perception. Doubling the distance to a sound source from some reference location makes the perceived sound ½ as loud, while halving the distance makes it twice as loud.

Do you need a green builder/remodeler
 in North Central Texas 
or the Dallas-Fort Worth area? 
Contact Terry Jensen 
972 251-1532 or 817 545-0140