Delay in auditory behaviour and preverbal vocalization in infants with unilateral hearing loss

Aim: To evaluate the impact of unilateral hearing loss (UHL) on early aural/oral communication skills of infants by comparing performance to infants with bilateral normal hearing (BNH). Method: Thirty-four infants with UHL (median age 9.4mo, 25th-75th centile 7.34-12.15) and 331 control infants with BNH (median age 9mo, 6.0-13.38) were divided into two subgroups based on risk factors known to cause developmental delay: low risk and high risk. Early auditory skills and preverbal vocalizations were assessed using two parent questionnaires: the Infant-Toddler Meaningful Auditory Integration Scale and the Production of Infants Scale Evaluation. Results: Of the infants with UHL, 21% showed delays in auditory behaviour and 41% delays in preverbal vocalizations, compared to their peers with BNH (p<0.01). After adjusting for risk level, delayed auditory behaviour and preverbal vocalizations were approximately four and nine times more common in infants with UHL compared to BNH respectively (p<0.01). Interpretation: This is the first study to show that infants with UHL are at higher risk of delay in early aural/oral communication abilities compared to infants with BNH even in the absence of other known risk factors for developmental delay. This has important implications for early intervention and habilitation of infants with UHL, in order to reduce some of the negative long-term consequences of what was once considered 'minor' hearing loss.