September 20, 2016.
By: Prajakta Bhogte
Modern technology has made it possible to obtain reliable information on how much your baby hears, at birth. Newborn Hearing screening is carried out on newborns, in countries such as the United States of America and in some countries in Western Europe. The hearing status of your newborn is valuable information, as is your baby’s blood group. Hospitals routinely identify the blood group of all their newborns; hearing screening should be a part of the battery of tests they routinely administer to newborns.
In India, newborn hearing screening is not mandatory. If you wish to test your newborn's hearing, or suspect hearing difficulty in your newborn, ask your baby’s doctor for a reliable hospital centre or clinic which carries out this test. Last month, we had a family of doctors bring across their two month old grandson to Sound Steps for hearing screening.
Those newborns who ‘refer’(or do not pass) the newborn hearing screening are re-screened. Those babies who ‘refer’ on the re-screening, are referred for further diagnostic testing.
These diagnostic tests of hearing are of two types:
1. Electro-physiological tests of hearing: a. ABR/BERA(hyperlink to website-What is ABR/BERA-tests of hearing for my baby) b. OAE (hyperlink to website-WHAT is OAE-tests of hearing for my baby) c. ASSR (hyperlink to website-What is ASSR/SSEP?-tests of hearing for my baby)
2. Behavioural Testing: a.Behavioural Observation Audiometry (BOA) b.Visual-Reinforcement Audiometry (VRA) c. Conditioned Play Audiometry (CPA)
In order to manage hearing loss in babies and young children, we need reliable information on how much the baby or child hears at each of the speech frequencies (which range from 250 Hz. To 8000Hz) in each of his or her ears. This is termed ‘ear specific and frequency specific information’.This information is obtained from Behavioural Testing. Electro- physiological testing such as ABR/BERA does not seek to obtain such specific information. Further, Electro-physiological testing does not require the baby or child, to participate; Behavioural testing, requires the baby or young child’s co-operation.
In order to obtain ear specific and frequency specific information, the sound stimulus must be delivered reliably to the individual ear of the baby or child.This is done via ear-inserts or insert earphones.
Behavioural Audiometry at Sound Steps.
Behavioural Testing is carried out based on the child’s cognitive age: the development of your child’s thinking skills determines the nature of the response that s/he can be expected to give to sound. The test procedure is then set up taking your baby or child’s cognitive or developmental age into account, as explained below:
|Cognitive Age||Expected Response to Sound||Name of test procedure|
|Birth to 6 months||Sucking response||Behavioural Observation Audiometry (BOA)|
|6 months to 36 months||Turns head in response to sound stimulus and is visually rewarded with a light that comes on||Visual-Reinforcement Audiometry (VRA)|
|36 months and above||Pick-up object and drop, in response to a sound stimulus. Called listen and drop task (Madell, J.).||Conditioned Play Audiometry(CPA)|
Testing babies and children takes time and skill. Behavioural testing is conducted over several sessions, given the short attention span of babies and young children.They must be allowed breaks as needed, so that baby and child settle happily into the testing procedure. Babies and children once comfortable, provide reliable audiological information.