I have inspected the first fitting of my Nexias using Smartfit. What confuses me is that there is a bone coduction measurement on the left ear but not on the right ear, as illustrated by the first image below. This seems to resutl in quite different gain curves for the hearing aids, as illustrated in the second image. The audi gave a diffuse explanation only stating that bone conduction was measured only on one side. So what is going on here. Is bone conduction equal for both sides? If that is the case why is it not copied over to the other ear as well. Since the audiograms of both ears are very similar, I do not understand why bone conduction is relevant for only one ear. Is this a mistake?
I donāt have an āofficialā answer, but I have only ever had bone conduction on one side in any of my hearing tests since I started wearing aids 30 years ago.
I donāt think that itsā the bone conduction results that are making the two sides look different, itās far more likely that your ears hear differently - and that is making the two sides look different.
Thank you for your reply. The reason I thougt that bone conduction made the two gains different is that the left ear, which has bone conduction measurements, has partially negative gains, while the right ear has only positive or zero gains. If the bone conduction is the same on both sides, I would have expected a similar bone cunduction compensation (partially negative gains) on the right ear as well. On the other hand, if the bone conduction varies and may be different on each side, then I do not understand why only one side is measured and why only the left side. I may overthink this, but I am curious and would appreciate a more convincing explanation tnan the one I obtained from my audi.
That looks very strange to me also, how do they sound to youā¦ equal volume right and left ?
maybe one of the Professionals will give an answer.
Did you set up another client in SmartFit and then not enter the BC, what is the difference you in the fit, quite a difference Iād think.
As I understand it (and Iām just a deaf guy with some curiosity), the bone conduction test is primarily diagnostic. Itās not so much looking for your hearing thresholds in the same way as the tone test, Itās more about comparing the two to see if there are large differences.
For example, if your BC test tracks closely to your tone test (like mine), your loss is likely sensorineural. The BC test by basically vibrating your skull at various frequencies, which effectively bypasses your inner hear hardware. If the BC is a lot better than the tone test, there may be something structural going on in your inner ear.
In other words, the tone test tries to determine if you are deaf. The BC test tries to determine why you are deaf.
With regard to the one-sided test, again - Iām not an audiologist - but my theory is that if your loss is largely similar from side to side (they will never match exactly), then it seems likely that the reason for the deafness is the same on both sides. I would imagine that they might do both sides if the tone test results were very different.
Thatās just my theory though.
Not even sure why audiologist put BC results on the audiogram as they are basically the same as AC results.
Before chemo took my hearing, I had a mixed loss but my BC and AC had a large difference so both were put on the audiogram.
BC test actually measures both ears unless masking is done as itās done via vibration so reaches both ears, no matter what side you put the painful headband on.
Thank you Allen and Zebras for your comments.
Well, what I did was to unckeck āUse Bone Cunductionā in User Preferences and then in Simulate mode Recalculate the first fit by the audi under Tools.This gave the results in the image below. Now all gains are positive or zero. So what is the conclusion? Should BC be used? If BC is used should it be used on both ears? If so, should the same BC data be used on both ears or should there be individually measured BC data for each ear?
BC is a measurement of what you hear via the sound hitting your skull rather than your hearing canals. It is relevant to the fitting because the fitting should back off the gain where your BC hearing is better (usually but not always in the bass end of things). The reason for measuring one side only is that you normally hear the BC sound in one ear because your skull connects to both by conduction through the bone and itās usually meaningless to adjust the ears separately.
If the audiogram is done fully, then the audi should use noise masking to identify what you are hearing in each ear. But this would be done for diagnostic reasons rather than to fit hearing aids I think.
Incidentally the effect of not having BC sound getting to your ears is often one reason, maybe the main reason, why streamed sound is often regarded as less satisfactory than sound picked up the hearing aid microphones (and the userās skull).
You can play around with the settings, but just ignoring the BC effect on the fitting is probably not going to help you.
I tr tried experimenting with BC in Target and Genie and just got further confused. Genie gives a warning if you enter BC NOT to?
Iām sure there is some inner workings going on here.
Perhaps @Volusiano or @Um_bongo could explain?
Itās going to up the prescription to the BC levels of gain. More aligned to the half gain rule than the third gain rule. That will give a higher prescription than youād usually expect; hence the warning.
Donāt stress it though, you can always turn it down. The inherent issue in fitting like this without REM is that you canāt tell if and where youāre overcooking the output.
Thank you for all the information on BC. However, unfortunately I am still confused. The audi applied BC, but only to the left ear. I do not understan why it was not copied over to the right ear as well. From the AC parts of the audiogram I can not see why the left ear was chosen instead of the right ear. To me they seem quite similar. So to very specific: if I pursue adding BC, should I apply the measured BC to both the left an right bart of the audiogram?
You gotta not āoverthinkā this, just donāt use the BC only the AC and now thereās no more confusion, itās just a first fitting as a DIY project right?
OK, I will rest my case. I am sure there are lots of other ways to get confused 
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How come he has 20 programing handles and I only have a choice of 6 or 10 ?
Same version of software ā¦
Do you have the exact same models, the 9 has this option.
I believe this is an option when you do a first fitting with SmartFit, but once the first fitting has been done with those aids at a lower number of handles, you cannot change to a higher number.
It has to do with the country you chose when you installed the SmartFit software.
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