In situ versus REM


#26

We do all our testing with inserts anyway. Closed domes can be flawed due to pressure on insertion issues or leakage in tall narrow canals.


#28

Does this imply that any PTA done without inserts potentially does have a risk of erroneous readings for lower frequencies?


#29

There’s greater variation especially in the lower pitches when you use a headset. The assumed volume is around 5cc though that’s hugely variable, the clamping force will alter for different heads and some ears just don’t seal as well due to harder cartilage and voids in the skull shape.

Inserts aren’t perfect, but they do eliminate lots of sources of error.


#30

Thankyou @Um_bongo and @Neville this discussion has helped me understand the inconsistency of AC at low frequencies better


#31

I ran the In Situ yesterday and applied the changes. I like the results. I am a little concerned at how much worse my low frequencies tested.

I would hate to think my low frequency hearing deteriorated that much since last February. Can I take it from reading this thread that it is normal for low frequencies to be worse when using In Situ?


#32

That’s meaningless without a BC figure - looking at it, either the loss has worsened or you’re testing under different venting conditions.

However, if you find the result more beneficial, you might be headed the right way WRT actual adjustment of the aids.


#33

The original audiogram (grey) was done in a booth with headphones only. The In-Situ (red & blue) was done with with power domes in my family room.

I know the power domes leak because I have elongated ear openings caused by swimmers ear and they don’t cause occlusion. They do reduce feedback over bass domes though.

The audi did do BC testing for a couple of frequencies when she did the hearing test. She didn’t bother to document any readings because she said there was no problem.

I guess from what you’re saying, I will need to another hearing test done to find out for sure.

From Nov. 2009 to Feb. 2018 : I had a loss of 15 decible in the 250 & 500 frequencies. It would be worrisome to find I have another 15 decible loss in those same frequencies over a 9 month period.


#34

I think it is the venting conditions that are responsible for the differences. I switched my 8 mm power domes with 6 mm double vent bass domes and ran the In-Situ Audiometry again. My results were even more varied in the low frequencies this time.

Note: I was wearing 6 mm double vent bass domes and still had power domes selected in Acoustics when I ran this In-Situ test.

I ran another test ( see my post below) where I have the same Base Domes selected in Acoustics and on the hearing aids prior to running In-Situ.


#35

Choose exactly the same acoustic fitting in software before starting the insitu that you are actually using. Do the readings change when you change different types of domes and molds in the acoustics option of the software before running the test? If yes then the software is probably giving you improved results if you tell the software that you are using double vented but actually using a closed mold. Do share your findings


#36

Ran the In-Situ again. This time with the Double Bass Dome selected. I did get slightly better results from having the correct domes selected prior to running In-Situ Audiometry.

I did the reverse. I was actually using Double Vented Base Domes, but still had Power Domes selected in Acoustics.

Note: The reading of 50 at 125 is wrong. The software wouldn’t let me increase to a db HL where I could hear the tone.


#37

This might imply that software generates interpolated tones for lower frequencies . It might not be the real decibels but the equivalent decibels for the acoustic fitting selected. Do check again with double vent selected in software and the most occluding actual fit you can do (closed custom mold would be ideal but even power domes should do). I suspect it might take your results closer to the original audio gram .


#38

I don’t think this is the case. I can decrease the db HL needed to hear the pulse tone by pressing on the Tragus and closing off any leakage from my ears. When I do this it takes my results close to my audiogram. This works regardless of which domes I have selected in Genie or have on my hearing aids,

This pretty much tells me my hearing hasn’t drastically changed in the low frequencies like I initially feared.


#39

Doctor it hurts when I do this. :slight_smile:
Good news.


#40

How does the first fit of the Marvel’s work in combination with an in situ?