Eilers RE, Oller DK. Infant vocalizations and the early diagnosis of severe hearing impairment. J Pediatr. 1994; 124(2): 199-203.
Findings from this study indicate that infants with normal hearing produce canonical vocalizations before 11 months of age, while infants with severe to profound hearing loss do not produce these vocalizations until they are 11 months of age or older. Authors conclude that otherwise healthy infants who do not produce canonical babbling by 11 months of age are likely at risk for hearing impairment, and should promptly be referred for audiologic evaluation.

Kent RD, Osberger MJ, Netsell R, Hustedde C. Phonetic development in identical twins differing in auditory function. J Speech Lang Hear Res. 1987; 52: 64-75.
This study compared the vocal development of twin boys: one with normal hearing and the other with profound bilateral hearing loss. Researchers collected vocal samples at 8, 12, and 15 months, and found acoustic-phonetic differences between them at each age. Authors discuss the implications of this study for the early identification of infants at risk for communication disorders.

Laing, E., Butterworth, G., Ansari, D., Gsödl, M., Longhi, E., Panagiotaki, G., Paterson, S. and Karmiloff-Smith, A.  Atypical development of language and social communication in toddlers with Williams syndrome. Developmental Science. 2002; 5(2): 233–246. 
The purpose of this study was to examine the social and interactive precursors to language that may contribute to late language onset and atypical linguistic development in toddlers with Williams syndrome (WS). Researchers found that toddlers with WS were impaired in triadic interactions and the comprehension and production of referential pointing.

Lieberman, A, HAtrak M, Mayberry R. Learning to look for language: Development of joint attention in young deaf children. Language Learning and Development. 2013: 10(1); 19-35.
Study of four deaf children during interactions with their deaf mothers. Gaze patterns observed in deaf children were not observed in a control group of hearing children, indicating that modality-specific patterns of joint attention behaviors emerge when the language of parent-infant interaction occurs in the visual mode.

Levin K. Babbling in infants with cerebral palsyClin Linguistic Phon. 1999; 13(4): 249-267.
This report describes the development of babbling in eight 1-year-old infants with cerebral palsy. Most subjects showed a delay in the onset of canonical babbling, and all subjects had a limited phonetic repertoire and only produced monosyllabic utterances. Study investigators believe these findings challenge the idea of babbling as a robust phenomenon and justify early intervention.

Mitchell S, Brian J, Zwaigenbaum L, Roberts W, Szatmari P, Smith I, Bryson S. Early language and communication development of infants later diagnosed with autism spectrum disorder. J Dev Behav Pediatr. 2006; 27(2): S69-S78.
This study confirms that delays in communication and language development can be identified early in children with ASD. Authors suggest that developmental surveillance should include monitoring for delays in gesture production, which may be among the earliest signs of ASD.

Nathani S, Oller DK, Neal AR. On the robustness of vocal development: An examination of infants with moderate-to-severe hearing loss and additional risk factors. J Speech Lang Hear Res. 2007; 50(6): 1425-1444.
Researchers evaluated vocal development in four infants with moderate-to-severe hearing loss. Subjects showed some delay in the onset of babbling, though the delay was much less than that observed in infants with deafness. Authors suggest further investigation of the effects of varying degrees of hearing loss on vocal development.

Polisenska, K, Kapalkova S. Language profiles in children with Down Syndrome and children with Language Impairment: Implications for early intervention. Research in Developmental Disabilities. 2014: 35(2); 373-82.
This study compared early language profiles of children with Down Syndrome or Language Impairment to typically developing children. Findings suggest that language intervention should be tailored to specific etiologies rather than focus on general communication strategies.

Rvachew S, Creighton D, Feldman N, Sauve R. Vocal development of infants with very low birth weight. Clin Linguist Phon. 2005; 19(4): 275-294.
This article describes the vocal development of healthy infants, relatively healthy pre-term infants with very low birth weights (VLBW), and pre-term infants with VLBW and bronchopulmonary dysplasia(BPD). At 18 months, pre-term infants with BPD had significantly smaller expressive vocabulary sizes than healthier pre-term infants and healthy full-term infants.

Sauer E, Levine S, Goldin-Meadow S. Early gesture predicts language delay in children with pre- or perinatal brain lesions. Child Dev. 2010; 81(2): 528-539.
In this study, researchers examined language outcomes in 11 children with pre- or perinatal unilateral brain lesions (PL) who produced a varying range of gestures at 18 months. The study authors found that gesture production at 18 months was predictive of language outcomes at 30 months for children with PL, suggesting that gesture may be a promising diagnostic tool for persistent language delays.

St. Clair MC, Pickles A, Durkin K, Conti-Ramsden G. A longitudinal study of behavioral, emotional, and social difficulties in individuals with a history of specific language impairment (SLI).  J Commun Disord. 2011; 44(2): 186-199.
This report found that individuals with a history of SLI have poorer long-term social and emotional outcomes, while behavioral difficulties seem to decrease by adolescence. Reading skills and expressive language were linked to behavioral problems, while pragmatic skills were related to difficulties in all three domains.

Tek S, Mesite L, Fein D. Longitudinal analyses of expressive language development reveal two distinct language profiles among young children with Autism Spectrum Disorders. Journal of Autism and Developmental Disorders. 2014: 44; 75-89.
In this study, researchers found that children with ASD present two distinct language profiles. Children with ASD who had higher verbal skills were comparable to typically developing children on most language measures, while children with ASD who had low verbal skills had flatter trajectories in most language measures.

Thal D, Tobias S, Morrison D. Language and gesture in late talkers: A 1-year follow-up. J Speech Lang Hear Res. 1990; 34: 604-612.
This purpose of this study was to explore language performance in children identified as late talkers. Children who eventually displayed persistent language delays showed early delays in language comprehension, and performed worse on gesture-related tasks compared to late talkers who eventually caught up to their peers.