The articulation index, also known as AI, is a measurement that indicates how well speech can be understood in noisy environments. It is a key factor in designing effective communication systems for individuals with hearing impairments. There are various synonyms for the term articulation index, including speech intelligibility index (SII), auditory-intelligibility index (AII), and modified rhyme test (MRT). Additionally, there are related terms such as the speech transmission index (STI) which is used to measure speech intelligibility in a sound system. These terms all refer to methods of evaluating speech clarity in different contexts and are important indicators for creating effective communication solutions.