The Infant Monitor of vocal Production (IMP) normative study: Important foundations

ABSTRACT

The purpose of this study was to establish a set of normative data (growth curve and centiles) for the Infant Monitor of vocal Production (IMP) using a representative population of infants with typically developing hearing. A linear mixed effect model and regression was used to derive ‘stage-for-age’ trajectory and growth centiles from the standard sequence of IMP assessment scores of 85 infants with normal hearing (age range 3–13 months). A significant linear relationship was demonstrated between IMP scores and infant age (p < .001). No significant relationship was found between IMP scores and gender, mono/bilingual language environment, singleton/sibling status, maternal education, or maternal work status. Inter-rater reliability and correlation for agreement was strong (0.94). These findings show that IMP assessment depicts the vocal development of infants with normal hearing as an hierarchical relationship between the complexity of infant vocal productions and infant age. Normative gains in vocal competency (−1SD/+1SD) approximated one IMP question per month of age from an infant’s baseline level of IMP achievement.

KEYWORDS:

• Infant vocal development
• assessment
• normal hearing
• deafness

Acknowledgements

The authors wish to sincerely thank the parents who gave of their time to participate in this study, and the early intervention Teachers of the Deaf who presented the IMP assessment in conversation with those parents. This project was supported by the Royal Institute for Deaf and Blind Children (RIDBC), Australia.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Robyn Cantle Moore has over 25 years of experience as an educator in the field of pediatric hearing impairment. She holds Master's degrees in Special Education (Sensory Disability), and in Educational Studies; and a Ph.D. in Education. Robyn is conjoint Lecturer/Coordinator of post-graduate courses in pediatric language development and family collaborative approaches to early childhood intervention for sensory disability (HI and VI) at RIDBC Renwick Centre for Research and Professional Education/University of Macquarie/University of Newcastle. As a researcher, she has developed specialized curriculum, parent education materials and assessment tools to guide early intervention and professional practice in the area of neonatal diagnosis and habilitation of hearing loss.

Kim Colyvas has wide-ranging expertize in the application of statistics across the fields of Psychology, Ecology and Biology, Health and Medicine, Linguistics and Speech pathology, Education and Business. As Consulting Unit Manager in the School of Mathematical and Physical Sciences at the University of Newcastle, he provides statistical process control and analysis of data support for research, and oversight of measurement systems and their performance.

ORCID

Robyn Cantle Moore http://orcid.org/0000-0002-8826-1242