What is insertion loss?

Insertion loss is a measure of how much sound reduction is achieved when an acoustic device—such as an acoustic louvre—is installed within a system. It represents the difference in sound level before and after the acoustic component is introduced.

In practical terms, insertion loss tells designers how many decibels (dB) of noise reduction a louvre will provide across specific frequencies. Because sound behaves differently at low, mid, and high frequencies, insertion loss is typically presented in octave bands (for example, 63Hz to 8kHz), rather than as a single-number rating.

Insertion loss differs from the Weighted Sound Reduction Index (Rw). Rw is commonly used for solid building elements such as walls or glazing, whereas insertion loss is more appropriate for systems where airflow must pass through the element—such as ventilation louvres or acoustic attenuators.

Testing is usually carried out in controlled laboratory conditions, where sound levels are measured before and after the acoustic louvre is installed within a test opening. The resulting data allows acoustic consultants to incorporate the louvre’s performance into broader plant noise calculations and environmental noise assessments.

It is important to understand that insertion loss values relate to the performance of the tested configuration. Real-world factors such as flanking transmission, installation detailing, and downstream ductwork can influence overall site performance.

At Solinear, our SoundEX acoustic louvre systems are supported by detailed octave band insertion loss data, enabling consultants to model plant noise reduction accurately and select systems that achieve planning compliance without unnecessary overspecification.