Normal bone conduction threshold?

[3littlemen]

Can anyone tell me what a normal bone conduction result is? Unmasked?

My son continues to receive varying results with all of his tests, but it is my understanding that bone conduction is very accurate, correct? Are BC tests ever wrong, open to interpretation by the tester, or is there a range they can be off by (like 5-10 dB)?

Any help is appreciated.

 

[Bottesini]

From what I know they can easily be off by over 10 db, are not very useful in mixed losses, and not good for high frequencies.

 

[3littlemen]

His BC during his second ABR under anesthesia was 30 dB unmasked.

I am just concerned, because yesterday he passed an OAE in both ears (he has never passed in the left ear before, and right ear is hit or miss) and then turned his head to every sound in the booth with sound field testing and responded at 10-20 dB each time, except for one time at 30 dB, but it was repeated later and he turned his head at 20 dB.

The audiologist is new for us, and she was wondering if I have been right and that it is that his ear canals are weird and are just beginning to grow and straighten out, allowing more sound. Would also explain his low frequency loss, since low freq sounds would be more muffled by ear probes.

The 2nd ABR showed that his loss was worse than the 1st ABR, but that just doesn't make sense compared with yesterday, and I always questioned that one for various reasons...audi always told me one thing and then conflicted what she said at other visits, etc.

So knowing the normal BC level is important for me in putting all of this together. I read a reference article online about a study where they concluded normal BC was 20 dB at 500Hz and 30 dB at 2000 Hz for infants...so if that is true, that is further evidence that he may not really have a permanent hearing loss...that it really is a problem with his canals. This was also the thoughts of the clinical director of training at Vivosonic, the test manufacturer. I called them in Canada and requested to talk to someone about the test after the first one. She said I was the only parent to ever call.

It is even weirder because I just met up with a mom and her daughter today because her daughter is going to babysit for me tomorrow. Just met them today for the first time, and her son has Down syndrome. Anyway, ABR on him as a baby showed he had a profound hearing loss. Well, turns out he failed because he has tiny ear canals and the sound was all muffled...which is exactly what I have thought all along about my son's.

I just wish they would figure it out already...I have been shouting ear canal, ear canal, ear canal to them for months, and they keep dismissing it. His canals are anterior and crescent-shaped. They are not circular and you can't see them when you look at his ear dead-on. This audiologist is the first to really listen to me, and the woman with Vivosonic, who has 15 years of experience in electrophysiology and working with the tests said it was possible too, but it has never been taken seriously with my other audiologist.

 

[Bottesini]

I have very small and malformed ear canals. I didn't grow out of them.

And I do have a mixed loss. I didn't know you could grow out of malformed ear canals.

 

[3littlemen]

Lol. Well, her explanation was that since he is growing, his ear canals are growing as well and that they could be letting more sound through now, thus his increased response. Or perhaps his ear canals are not a problem other than being tiny, but that the probes are still not positioned correctly and are hitting the skin.

Anyway, I had also come across a blog before about a little boy who had atresia and had his widened and didn't need his hearing aid anymore, so I know it is correctable in some cases at least.

 

[blank canvas]

Lol. Well, her explanation was that since he is growing, his ear canals are growing as well and that they could be letting more sound through now, thus his increased response. Or perhaps his ear canals are not a problem other than being tiny, but that the probes are still not positioned correctly and are hitting the skin.

Anyway, I had also come across a blog before about a little boy who had atresia and had his widened and didn't need his hearing aid anymore, so I know it is correctable in some cases at least.

Well, it depends on if it is only a conductive loss, my daughter has atresia/microtia she has no ear canals what so ever. But even if she were to have reconstructive surgery her hearing would only improve slightly because she has no ossicles and a bioplastic cochlea.

Has there been any consistency with his hearing tests? I'm amazed at how many he has had, my daughter had only two tests by the time she was 2 years old. Are they on your request or the doctors?

 

[3littlemen]

He failed the newborn screening like 3 times, then we got the first ABR which showed normal hearing in the right ear in all but 1 pitch. The left ear was moderate loss in 2 or 3 pitches. So they said he had mild-to-moderate reverse slope loss. Even before he had his first OAE, I felt like his ear canals were strange. A friend noticed it too. So, the day he was born I thought his ear canals were different. I guess they would look normal to someone not observant, but they definitely are tiny and crescent-like.

After the first ABR, with my concerns about the test, my pediatrician sent me to another ENT who used another audiologist from the practice with the first audi who performed the first ABR. We just wanted another test to confirm the first. Between the first and second ABR he passed OAEs in his right ear and almost passed on the left a couple times, but didn't. The 2nd ABR was vastly different than the first. Still mild-to-moderate, but the right ear was the worst ear, and it even dipped to moderately severe in one pitch. I was shocked. Of course, they said his hearing could have gotten worse, which I knew was a possibility, but months later, how can that be when he passed in both ears and did so well in the booth? I had doubts about the 2nd ABR, though, and recently requested a new audiologist and just saw her for the first time yesterday. The other audi basically told me one thing for months and then changed her story or mind or got confused. She had the right hearing aid set louder than the left because it was the "worst" ear, but then the last time I saw her she said it was the better ear. Well, which is it???

 

[3littlemen]

And yes, if you take the 2nd ABR out of the equation, the right ear has always been a little better. Even yesterday with the OAE that he passed, the right ear had a more robust passing response, she said. But both were still passes.

Until yesterday, he had never gotten a pass on the left. When he was 3 months and younger he could not pass them at all, but at 4 months he had several OAEs that he passed on the right and has passed from then on.

 

[blank canvas]

He failed the newborn screening like 3 times, then we got the first ABR which showed normal hearing in the right ear in all but 1 pitch. The left ear was moderate loss in 2 or 3 pitches. So they said he had mild-to-moderate reverse slope loss. Even before he had his first OAE, I felt like his ear canals were strange. A friend noticed it too. So, the day he was born I thought his ear canals were different. I guess they would look normal to someone not observant, but they definitely are tiny and crescent-like.

After the first ABR, with my concerns about the test, my pediatrician sent me to another ENT who used another audiologist from the practice with the first audi who performed the first ABR. We just wanted another test to confirm the first. Between the first and second ABR he passed OAEs in his right ear and almost passed on the left a couple times, but didn't. The 2nd ABR was vastly different than the first. Still mild-to-moderate, but the right ear was the worst ear, and it even dipped to moderately severe in one pitch. I was shocked. Of course, they said his hearing could have gotten worse, which I knew was a possibility, but months later, how can that be when he passed in both ears and did so well in the booth? I had doubts about the 2nd ABR, though, and recently requested a new audiologist and just saw her for the first time yesterday. The other audi basically told me one thing for months and then changed her story or mind or got confused. She had the right hearing aid set louder than the left because it was the "worst" ear, but then the last time I saw her she said it was the better ear. Well, which is it???

Well, my daughters hearing tests are always 'better' in the sound booth, mine are too, but thats because it is a sound booth meaning it blocks out all outside noise. So since the world is nothing like a sound booth its hard to base too much off of that, my daughters audiograms actually have always shown 10dec higher within a sound booth compared to a test given in the office where her hearing drops the 10dec I consider this one to be more accurate based on the fact that the world is not quite and we rarely hang out in sound booths...