08-22-2014, 02:48 PM
Airborne sound insulation
When a sound wave is incidental upon a partition between two spaces, part of it is reflected and part of it is transmitted through the partition.
R = 10log10 W1/W2
![[Image: soundinsulation2.jpg]](http://www.frontdesk.co.in/big/soundinsulation2.jpg)
For single leaf structures, such as a homogenous concrete wall, the transmission follows the mass law, that is, the more massive the structure, the smaller the quantity of transmitted sound.
In case of lightweight structures consisting of multiple layers, such as a gypsum wall, the spring-mass law is applicable. If highly absorbent material such as stone wool is used as the spring in a double leaf wall, the sound insulation improves. The wider the cavity, the greater the benefit from stone wool will be. Typically, a 5 – 10 dB increase in R can be achieved with a filled cavity compared to an empty one. The figure below shows a single leaf structure and a double leaf structure with the same total weight.
When a sound wave is incidental upon a partition between two spaces, part of it is reflected and part of it is transmitted through the partition.
R = 10log10 W1/W2
For single leaf structures, such as a homogenous concrete wall, the transmission follows the mass law, that is, the more massive the structure, the smaller the quantity of transmitted sound.
In case of lightweight structures consisting of multiple layers, such as a gypsum wall, the spring-mass law is applicable. If highly absorbent material such as stone wool is used as the spring in a double leaf wall, the sound insulation improves. The wider the cavity, the greater the benefit from stone wool will be. Typically, a 5 – 10 dB increase in R can be achieved with a filled cavity compared to an empty one. The figure below shows a single leaf structure and a double leaf structure with the same total weight.