Recently I was fitted with an Widex Inteo CIC hearing aid. One of the main reasons that I chose that aid was that the specifications indicated that it had a very high maximum gain (61 DB using the ear simulator results) as compared to most other CIC aids that usually have a maximum gain of no more than 45 DB.
I wanted the high gain since I was fitted with a Siemens CIC aid about 5 years ago but I couldn’t see any difference in my hearing ability.
Between the frequency range of 1000-3000 Hz, I have a hearing loss of about 70 DB.
When I tried the Widex Inteo CIC aids, my hearing improved in many situations (I was much happier with these aids than with the Siemens aids) but was still far from perfect. I started to investigate how the aids were performing. I used the following program to determine how the aids were performing.
I connected a high quality cupped headphones to my notebook computer, closed all the windows, and turned off anything that would make noise. I plotted my hearing (both without and with hearing aids) by clicking on the lowest possible DB on the chart for each frequency until I could no longer hear the sound. I repeated that process many times over many days to make sure that my readings were as accurate as possible (all graphs were almost exactly the same). Since the chart is not calibrated, I needed to figure out a way to calibrate the graph chart. Since my audiogram from the audiologist indicates that my hearing declined about 70 DB between 1000-3000 Hz and my Test graph (without aids in my ears) indicated about a decline of 42 DB over the same range, I calculated that each increment of Test graph indicated a 5 DB change instead of 3 DB as indicated on Test graph (70/42*3).
Although this test is not as accurate as the audiogram taken at the audiologists office, it should be accurate enough for what I want to determine.
Now I calculated the DB difference between each of the frequencies on the graph that was produced without my hearing aids and the graph that was produced with my hearing aids in my ears. I was surprised to see that the gain indicated was only 20 DB at 1500 Hz, 20 DB at 2000 Hz, and 25 DB at 3000 Hz but the gain at 4000 Hz was 40 DB and the gain at 6000 Hz was 60 DB (this did not even show on the graph without my hearing aids).
I said “what is going on here”? I reran the tests over and over again but the results were always the same.
If the resulting gain was about 40 DB, I may have suspected that marketing was advertising fiqures that weren’t accurate. But at only a 20 DB gain, that would be a major stretch even for most marketing people.
I also noticed that the fitting range did not match the increase in gain (indicated a maximum of 75 DB and should indicate a maximum of 85 DB) due to the following statement from the Widex documentation.
The maximum available gain is substantially increased. Indeed, the Multi-directional active feedback cancelling yields an average of 15 dB more usable gain - SuperGain - before feedback occurs.
So I asked myself, what is the problem? Why is the fitting range so low? Why is the fitting range 75 DB instead of 85 DB? Why is the gain only about 20 DB at 1500 Hz, 2000 Hz, and 3000 Hz? Why can frequencies at 6000 Hz produce a gain of 60 DB? Is the gain reduced for some frequencies due to feedback? Is the problem caused by the channel design? Did the audiologist set up the aids incorrectly? Is there a design problem in the software? Is it possible that my ears are so damaged at some frequencies that a 60 DB increase in SPL (sound pressure level) will not produce a similar response in my ear?
I’m stumped. Does anyone have any ideas? Has anyone had their hearing tested with their aids in the ears? If you did, what were the results as compared to your original audiogram?
I’m going to see the audiologist on Tuesday so I’d like to determine what I should do. I’d like to determine if I should try another brand of aid but if they all act similarly, it would be a waste of time.
Will open fit hearings aids work significantly better even though their maximum fitting range is at most 80 DB (some are as low as 70 DB) and have a lower maximum gain than this aid?