Measuring speech intelligibility with deaf and hard-of-hearing children: A systematic review.

56.9% of included studies did not provide precise age information for participants at the time of testing, making it hard to know exactly which age group each result applies to. 65.7% of studies did not explicitly report pure-tone averages, so the severity of hearing loss varied widely and is hard to account for when comparing results. No studies in the review measured suprasegmental features of speech (intonation, stress, rhythm), which the authors note can greatly impact intelligibility. Studies where more than half the participants were 13 or older were excluded, so measures validated only in adolescents or adults were not captured. Many studies used custom or unnamed rating scales without providing the actual scale in the article, making it impossible to verify what was being measured.

Do not treat the Speech Intelligibility Rating scale as the validated standard for deaf children simply because it appears in the most studies. The review found it is the most used, but its psychometric properties in languages other than English are limited, and no single measure has been established as the gold standard for this population.