Until recently, no studies have examined vocabulary outcomes of children with hearing loss that have met all three components of the EHDI guidelines:

1. Screening by 1 month
2. Diagnosis by 3 months
3. Intervention by 6 months 

Yoshinaga-Itano et al (2017) examined the impact of the EHDI guidelines on vocabulary outcomes in 448 children with a bilateral hearing loss that was part of the National Early Childhood Assessment Project. The findings demonstrated that vocabulary quotients were significantly higher for children who met the EHDI guidelines, other predictors included: age, mild-to-moderate hearing loss, parents who were deaf or hard of hearing, mothers with higher education, and had no additional disabilities. Even after controlling these predictors EHDI guidelines had a significant impact on vocabulary outcomes.

Reference

Yoshinaga-Itano et al. (2017) Early Hearing Detection and Vocabulary of Children with Hearing Loss. Pediatrics, Epub 2017, Jul 8.