Revisiting 0db aided hearing with HAs. Internal HA noise limiter?

D

deafdude1

New Member
Joined
Feb 24, 2009
Messages
1,268
Reaction score
0
http://www.audiologyonline.com/theHearingJournal/pdfs/HJ2003_10_pg46-47.pdf

http://www.rehab.research.va.gov/jour/96/33/4/pdf/macrea1.pdf

http://www.alldeaf.com/hearing-aids-cochlear-implants/67622-move-over-cyborg-queen-ambling-rambler-sets-new-ci-record-5db.html

I posted about this before and didn't get any good answers. Does anyone understand the above 2 articles on hearing aid internal noise? Isn't CI subject to the same noise? If so, how did she get 0db in several frequencies and -5 in one? I would like to learn more about the best possible aided hearing one can have, especially for mild and moderate losses. I did read that those who hear 25db or better unaided don't need amplification and they may just end up hearing the internal HA noise anyway. How do those with just high frequency losses handle HAs? I also read many with just high frequency losses don't even bother with HAs as they hear great already(such as my dad) and that HAs are more of an annoyance than help.
 
What the first two articles are talking about is microphone noise floor. For the whole device it is called the signal-to-noise ratio or S/N. In practice it is usually people with a mild hearing loss that can hear the very low level noise that is coming from the microphone pre-amplifier to the hearing aid receiver. However, if the user has a severe or profound hearing loss it is unlikely to pick up the noise due to the more limited dynamic range of a person with profound hearing loss. The noise is usually a form of hiss. If you have an audio system connected to speakers at home, you can sometimes hear the very faint hiss with the gain or volume at maximum if you put your ear close to the speaker. This will only work if you try it when nothing is playing on the audio system (e.g., no music). That would be part of the signal-to-noise ratio of the device. While manufactures of digital aids uses compression in aids to reduce recruitment, a few aids also have an option of downward expansion. Downward expansion further reduces the noise floor, but at some expense of low level signals in the environment.
The issue I am having is that the Freedom microphones on my implant are quite sensitive to wind noise. Each time I walk outside when there is a breeze it will sometimes overpower the conversation I am having with another person. One method to reduce this effect was to ask my audiologist to increase the maxima so that more electrodes can be fired as needed. My hearing aids also have some sensitivity to wind noise, but it is a bit easier to reduce by facing the user in a different direction since the microphone in a hearing aid is more directional that of my CI implant which also has far greater sensitivity to sounds in nature, such as the sound my jeans make while walking. The shoes also make quite a bit of noise while I am walking on a gravel trail.
 
dd1,

You asked if CIs should have the same problem as HAs. Yes and no. A HA is an amplifier of sounds and thus the issues as explained in the two pdf articles.

A CI is a different beast. It is not amplifying as much as it is stimulating the cochlea. The so called "volume" control on a CI is far less in terms of wattage in the circuitry than that of a HA therefore less an issue in respect to external/internal noise. I'm sure it is there but so low for most that it is not noticeable.

I work in an extremely quiet environment and like to hear at a higher "volume" than most. I never hear the external/internal noise mentioned in the articles. I do notice the small noises such as my CI processor rubbing my hair, myself breathing sometimes, noise from my laptop computer at work and etc.
 
Back
Top