Hearing aid fitting and developmental outcomes of children fit according to either the NAL or DSL prescription: fit-to-target, audibility, speech and language abilities.

All children were fitted by one government-funded service using a consistent protocol, so the results may not apply to clinics with more variable fitting practices. The children were all fitted before age 3 and had bilateral hearing loss, so the study does not show what happens for children fitted later or with unilateral loss. Outcomes were measured only around age 5, so long-term school-age effects are unknown. The parent-rated difference favored DSL, but direct speech and language tests did not show a difference, so the everyday listening finding should not be read as evidence of better language or speech ability. The study combined different versions of NAL and DSL prescriptions in the analyses, so version-specific fitting effects are not separated.

Do not conclude that DSL improves speech or language development because parent ratings were higher. The direct tests showed no difference between prescriptions, and the audibility advantage did not match better measured speech and language results.