How is the articulation index measured?

The articulation index (AI) is a numerical representation of speech intelligibility, usually expressed as a value between 0 and 1. It is measured by assessing the amount of speech information transmitted through a communication channel, factoring in background noise, reverberation, and the characteristics of the listener's hearing ability. The AI is calculated using a formula that incorporates the speech signal's frequency components and the listener's sensitivity to those frequencies. Higher AI values indicate better speech intelligibility.