Auditory behaviour index in infants

Ksh Rameshori Devi *

“When someone in the family has a hearing loss, the entire family has a hearing problem.”
Dr Mark Ross

The human ear has evolved in such a way as to tune with sensitivity to the range of human speech. The hearing sense is the first sense organ among other senses that develops in the human being. It had been estimated in a study by UNICEF that nearly 35 million children suffer from hearing impairment of various grades in India.

In a survey, 4 out of 1000 children born in India were found to have severe to profound hearing loss. As per the country-wide sample survey conducted by the Government of India in 2011 (NSSO, 2011), the census listed hearing impairment as the second leading disability with a high prevalence of 18.9%.

It is estimated that 5.3% of the world’s population is affected by hearing loss, which is most evident in South Asia, Asia Pacific, and suburban Africa (WHO, 2012). According to the 2011 census in Manipur, 0.1% male and 0.2 % female has a hearing impairment.

The Newborn Screening Program at RIMS, Imphal carried out a prospective study between April 2014 and March 2015. At this particular time, a total of 4225 newborns were screened for Hearing loss, and among this 10.6% were under the High-Risk factor.

Hearing loss in children is a cause for parental as well as physician concern. From 10 to 26% of hearing loss in children is congenital (i.e., at birth or early childhood). Congenital hearing loss can be due to acquired (nongenetic) or to genetic causes; it can be attributed to prenatal, perinatal, or postnatal causes.

Many studies have shown that children with congenital or early acquired hearing loss are identified only after a delay. Early detection of congenital or early acquired hearing loss remains a serious and unsolved problem.

Early in a child’s development, they will be exposed to many new and wonderful sounds—the most important being speech. For infants to fully develop speech and language skills, they must be able to hear adequately.

The outline below is provided as rough estimates of normal auditory and speech development.

Birth to 3rd month : When a loud sound is made such as a clap, alarm, etc. the baby will awaken when asleep or may move and begin to wake up. At times on hearing loud sounds the baby will get startled, eye blinks, eye-widening, and start crying. Your child enjoys “cooing” (makes cooing sounds) and “gurgling” (sounds resembling gurgle).

3rd to 6th month : The child normally recognizes the mother’s voice. If a child is crying, she/he usually stops when hears her/his mother’s voice. Baby smiles when spoken to, stops playing and appears to listen to sounds, especially when pleasant and new sounds are made. For example–the sound of new toys. Baby responds to her mother’s voice by making pleasurable sounds. The rudimentary head turn starts by 4 months.

6th to 9th month : The child will turn her head laterally towards the sound source and her interest in listening to sources of new sounds continues. Directly localize to side and indirectly localize above ear level. The child will enjoy making different sounds and continue to babble.

She tries to imitate if the Parent makes sounds resembling those made by the child. She can vocalize emotional satisfaction or dissatisfaction. That is when she is happy, her smile is accompanied by vocalization (voice) and when unhappy or uncomfortable she usually cries.

9th to 18th month : The child will look up when the Parent calls. Directly localizes to side and below ear level and indirectly localizes above ear level. The child understands words like ‘no’. She will also respond to simple commands like ‘open your mouth’, ‘close your eyes, and likewise.

She starts using her voice for getting attention; first word is usually heard at any time within this period and imitates some of the sounds that the Parent makes. By 18 months the child’s vocabulary (use of meaningful words) increases gradually.

18th month to 2 1/2 year : The child will begin to respond to requests like ‘give me’; she can also respond to commands like ‘bring the ball’ and throws it when asked to. The child can point to things that are named. She can combine words into sentences for example ‘papa come’. She can name a few common animals, fruits, etc, and name objects and describe them by using adjectives and adverbs like big\more\nice.

Joint Committee on Infant Hearing (JCIH, 2007) has recommended that all the newborns should undergo screening by one month of age and detailed evaluation of referred newborns before 3 months of age. It is also recommended that those identified with permanent hearing loss should begin intervention by 6 months.

As per the recommendation of the WHO (2009), facilitating early hearing detection and intervention is crucial in the first month of life. The first 3 years of life is considered the most intensive and critical period for acquiring speech and language skills in newborns and infants (NIDCD, 2014).

As the Parent looks out for any sign and symptom of hearing loss by following the Auditory Behavior Index so, timely detection and close follow-up could be done to improve the overall development in terms of speech, language, social, academic, emotional, and cognitive skills of the child.