Infant cooing, babbling tied to hearing ability

Babies explore their own vocalisations and learn through their capacity to produce sounds, a new study has found.
University of Missouri researchers have found that infant vocalisations are primarily motivated by babies' ability to hear their own babbling.
They found that infants with profound hearing loss who received cochlear implants to help correct their hearing soon reached the vocalisation levels of their hearing peers, putting them on track for language development.
"Hearing is a critical aspect of infants' motivation to make early sounds," said Mary Fagan, an assistant professor in the Department of Communication Science and Disorders in the MU School of Health Professions.

"This study shows babies are interested in speech-like sounds and that they increase their babbling when they can hear," she said.
Fagan studied the vocalisations of 27 hearing infants and 16 infants with profound hearing loss who were candidates for cochlear implants, which are small electronic devices embedded into the bone behind the ear that replace some functions of the damaged inner ear.

She found that infants with profound hearing loss vocalised significantly less than hearing infants.
However, when the infants with profound hearing loss received cochlear implants, the infants' vocalisations increased to the same levels as their hearing peers within four months of receiving the implants.

"After the infants received their cochlear implants, the significant difference in overall vocalisation quantity was no longer evident," Fagan said.
"These findings support the importance of early hearing screenings and early cochlear implantation," she said.
Fagan found that non-speech-like sounds such as crying, laughing and raspberry sounds, were not affected by infants' hearing ability.
She said this finding highlights babies are more interested in speech-like sounds since they increase their production of those sounds such as babbling when they can hear.
The study was published in the Journal of Experimental Child Psychology.