Our Recent Posts

Archive

Tags

No tags yet.

Audiology

So hearing tests. All babies born in the uk have a newborn hearing screening test. This is usually done in the hospital soon after birth and before the family is discharged.

Caleb failed this.

Twice.

The initial hearing test is a really simple procedure. A tiny probe is placed in the babies ear which plays a tone. This probe then picks up the tiny movements of the hairs in the Cochlea reacting to the sound. Caleb had this done on the second day after he was born. He was good as gold and just lay there with no reaction at all. He wiggled a tiny bit but had no objection to having the tiny probes placed in his ears like little I-phone ear buds. But there was nothing, no reading, no reaction, nothing. The tester spent around 45 minutes with us trying both ears and different probes as his ear canals were so tiny, but still no reading could be taken. She talked to us about him and that a failed result did not mean he had hearing loss or was deaf. A failed newborn hearing test can be quite common especially in preterm babies and those born by caesarean as they don’t have the fluid squeezed out as they would if it had been a normal birth. The audiologist was really kind and said as I was going to be in for a few days yet that she would come back tomorrow and try again in the hope some of the fluid had dried up and drained out.

The next day she came back and did the test again, and again there was no reading. So another approach was tried. This is where a small electrode is placed on the babies head and sound is played into their ears. This electrode picks up the brain waves and shows if there is a reaction in the brain to the sounds being played into the ears. This again got no response. But again the audiologist was not surprised and said she would do me a referral so that he could be retested at a full audiology appointment in a few weeks. There they could do a full test with all the best equipment rather than the little portable one she had with her.

I was not too worried as Caleb although didn’t seem to be reacting to our voices did have a startle reflex to us sneezing or sudden loud noises.

So a few weeks later we went back to the hospital to have a further hearing test. Caleb had shown signs of reacting more to sounds but still only to loud sounds. At this appointment the audiologist wanted to repeat the more detailed hearing test where they look at the brain waves. For this Caleb needed to have electrodes placed behind his ears, on his fore head and cheeks. These were sticky pads which had to be stuck onto really clean skin. So my two week old had a exfoliating facial before the probes were stuck to him. This was to get the best electrical contact with the skin so that the impulses could be picked up. These little pads were then connected to wires which fed into a laptop. Some small probes where then placed into each ear and the tones played on each side separately to take the readings. These tones are played quite loud to start with to get a reading and once it is established that the brain is reacting to the sound traveling through the ear then the tones are reduced in stages to gauge how quiet a sound the brain is reacting to. First of all the audiologist said he was not deaf which is a good start. She was getting good reading from both ears on the louder sounds. But the left ear was performing better than the right. She was getting reading down to 35 decibels on the right ear and 25 on the left which is equivalent to quiet talking. The audiologist felt that this was a good result and although she couldn’t get any lower readings she thought that as he grew and his ear canals widened his hearing would improve. So another appointment was made for when he was 8 months old.

Fast forward a few months and its time for this 8 month appointment. Caleb has changed a great deal in this time and has turned into a funny cheeky little monkey. He has started to sit up by himself so most of this test was done with him sat on my lap. This test was a little different. We were taken into a sound proof room with two audiologists. One to carry out the tests and one to observe Calebs reactions. After having a good look in each ear to check for signs of infection the first test they did was to put another type of probe in each ear to test the air pressure behind the ear drum in the middle ear. This is called Tympanometry. This basically blows air at a certain pressure at the eardrum and measures the pressure of the air that is reflected back. In a normal ear behind the drum is more air which comes up your eustation tube from the back of your throat. ( this is why your ears pop as you gain altitude on an aeroplane). If this area is filled with air then the probe blows air at the ear drum it should bounce back like a mini trampoline and be measured by the probe. A lot of young children have glue ear which is where this area behind the ear drum is filled with fluid. This can cause the ear drum to bulge or the pressure behind the drum to be higher than it should be. Therefore when the probe blows the air at it, it won’t bounce back as it should. Anyway Caleb passes this test with flying colours so no sign of glue ear.

The next test was more to gauge his reaction to sounds. So rather than testing his brain waves to see if the sound was getting through, this was to assess if he was processing the sounds and reacting to them. Basically they played sounds by the side of his head to see if he would look in that direction. He did not. Not once did he turn his head to any of the sound whether it was loud or quiet. He did however stop whatever he was doing and look like he was listening, and he did this down to some very quiet sounds. To be fair though I am not surprised he didn’t turn to the sounds. The tool the audiologist was using looked like a metal detector the security use on you in airports and it made a sound very similar to the sound of the tricorder scanner on the original start trek series. Caleb has never watched star trek so it would be a novel sound to him so probably not very interesting. So the conclusion was that yes he can hear but they couldn’t tell me if he had better hearing in one side or the other or if he could hear really quiet sounds. That would have to be monitored as he gets older and is able to react to sounds better. So I guess we wait for either another hearing appointment or for his speech to start developing before we know more.