Anjali, aged 38 years, lost her hearing during childhood following a fever. Years of speech therapy helped her attain a speech that was recognisable, assisted by lip reading with minimal amplification via hearing aids. But in order to communicate she had to directly face the person to lip read. This would be strenuous in dim ambient light during the late evening and at night. Further, she would not be able to hear if someone called her from the side or from behind and hence had no sense of sound direction. The inability to hear and communicate well with the outside world led to occasional bouts of depression and loss of self-confidence.
But after the cochlear implant surgery in both ears, there is a remarkable improvement in sound and language recognition which has boosted her self-confidence.
Rohan was three years old when he was diagnosed with severe hearing loss in both ears. From age one, his mother and grandparents had a suspicion when they noticed his lack of response to noise and poor speech development. When compared to children of his own age group, he seemed to be way behind in speech. But things changed when he underwent the cochlear implant surgery.
How do we hear?
The ear can be divided into three parts - the outer ear, middle and inner ear.
The outer ear consists of the ear canal and eardrum. Sound travels down the ear canal, striking the eardrum and causing it to vibrate. The middle ear is a space behind the eardrum that contains three small bones called ossicles, which are connected to the eardrum at one end and to the cochlea (inner ear) at the other end. Cochlea is a snail-shaped, curled tube located in the inner ear. It converts sound vibrations to electrical impulses and transmit them to the hearing nerve, which sends the signals to the brain where they are translated into recognisable sounds.
When the cochlea does not work properly, sound vibration is not converted into electrical impulse and the person cannot hear as the hearing nerve is not stimulated.
What is a cochlear implant?
Cochlear implant is an electronic device that replaces the function of the damaged cochlea. Unlike hearing aids, which make sounds louder, cochlear implants do the work of damaged parts of the cochlea by transforming sound signals into electrical impulses and then directly transmitting these impulses through the hearing nerve to the brain.
In the first few years of life, hearing is a critical part of a child’s social, emotional, and cognitive development. Even partial hearing loss can affect a child’s ability to speak and understand language. When hearing loss is detected late, language development is delayed affecting a child’s ability to learn and perform in school.
Most newborns startle or ‘jump’ when they hear sudden loud noises. When the baby is three months old, she or he recognises a parent’s voice and at six months, an infant can usually turn his or her eyes or head toward a sound. A one-year-old can produce a few words such as ‘Amma’ or ‘bye-bye’.
Warning signs of a possible problem
If an infant does not respond to a sound, it should be considered seriously. If children 12 to 24 months of age do not show gestures such as pointing or waving; if children 18 months or older have trouble imitating sounds and have difficulty in understanding simple verbal requests, they need further evaluation.
How a cochlear implant works:
The cochlear implant consists of two components, an internal implant surgically inserted inside the head and an external sound processor, which is worn behind the ear. The external sound processor has a microphone that picks up the sound, which is analysed and converted into electrical signals that are transmitted to the internal implant. These signals stimulate the hearing nerve and the message is sent to the brain. The brain interprets the sound and the person hears.
Three to four weeks after surgery, the sound processor is connected with the implant and is programmed. During the programming process, the user attends speech and language therapy sessions to help identify and interpret the new sounds.
In addition, an important part of the therapy includes parent education and training. These sessions last from six months to a year. In many cases, therapy has helped children with cochlear implants develop speech and language on a par with their peers and attend regular schools.