- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 02 Nov 2020
Sound reduction index (SRI)
The sound reduction index (SRI) is a measure of the reduction in the intensity of sound when it passes through part of a building; in other words, the level of sound insulation provided. It is the difference between the sound intensity that hits one side of an object (such as a wall, door, window, partition and so on) and the sound intensity measured on the other side, expressed in decibels (dB).
When sound hits the surface of a material, some will be reflected, some will be absorbed by the material and some will be transmitted through it. By determining the SRI, the effectiveness of the element as an insulator (the amount of sound that it has prevented from passing from one side to another) can be assessed.
In the USA, the sound transmission class rating is typically measured as the Noise Reduction Coeffiecient (NRC). This measurement is in the process of transitioning to the Sound Absorption Average (SAA).
 Related articles on Designing Buildings Wiki
Featured articles and news
Proper materials and maintenance can help reduce rust.
Is the construction sector responding to calls for ED&I?
Engineers pay tribute by sharing their memories.
The hidden price of infrastructure.
BREEAM incorporates wellbeing into its Building Back Better programme.
Administration signals policy changes on some building-related issues.
From inns and coaching houses to boutiques.
Survey reveals green skills gap.
America's economic collapse produced scores of PWA Moderne projects.
The benefits of glowing aggregates and cement.
Urgent need for open communication to address mental health issues.