The switch-on moment: what happens when a deaf child hears for the first time

In clinics around the world, audiologists will tell you that the switch-on is the part of their job they never tire of. It is the moment, usually three to four weeks after surgery, when the cochlear implant is activated for the first time. It is clinical, precise, and methodical. And it is one of the most emotional experiences a human being can witness.

The appointment begins quietly. The audiologist connects a small programming cable to the external processor and runs software that maps the device to the patient's specific nerve responses. Every cochlear implant user is different - the number of surviving nerve fibres, the shape of the cochlea, the sensitivity of the hearing nerve. The audiologist calibrates each electrode individually, finding the softest signal the nerve responds to and the loudest level that is comfortable.

Then the processor is disconnected from the computer. Placed behind the ear. Held in position by a magnet.

And switched on.

For a very young child, the reaction is instinctive. They freeze. Their eyes widen. They look for the source of the sound - a parent's voice, the audiologist speaking their name - as if they cannot quite believe the world has changed. Some laugh. Some cry. Some simply stare, overwhelmed.

For an older child or an adult who lost their hearing, the moment is different but no less profound. One patient described hearing her granddaughter's voice for the first time as 'finding something I didn't know I had lost.'

"When I performed the first successful multi-channel cochlear implant in 1978, I dared to hope it might give people some awareness of sound. What we could not have predicted was how completely it would restore speech understanding - and with it, entire lives." - Prof. Graeme Clark AC, University of Melbourne — Pioneer of the cochlear implant

The switch-on is not the end of the journey. In the weeks that follow, the brain works to interpret signals it has never received before, or has not received in years. Sounds may seem strange, mechanical, or unfamiliar. Voices take time to recognise. Music, at first, may sound unlike music at all.

But the brain adapts. And with each mapping session - fine-tuning the device to the patient's evolving responses - the world becomes clearer.

Your donation to Sound of Hope funds this moment. The switch-on. The first sound. The beginning of a lifetime of hearing.

Expert source: Prof. Graeme Clark AC, University of Melbourne - Pioneer of the multi-channel cochlear implant