If someone has 70db HL and gets 70db HA gain, does he hear 0db?

@Deaf123 said:

http://books.google.com/books?id=_tcPcPTwNQoC&lpg=PA444&ots=c1Nq2tYgCc&dq=speech%20%25%20hearing%20loss%20pta&pg=PA450#v=onepage&q=&f=false

Does anyone know why? Is there a way around this by reducing SPL/MPO? It goes on to say that hearing at 0db overamplifys(too loud) you and results in distortion. If someone has 70db HL and a 0db sound is amplified to 70db, that person should just barely hear a 0db sound. How can it be too loud? As for a 30db sound, don’t give 70db gain, use compression so a 30db sound is only getting 55db gain, but a 0db sound gets the full 70db gain.

If someone can’t benefit from hearing at 0db, would 5db or 10db be far easier to be able to tolerate? Also why aren’t maximum gains always used in severe-profound hearing losses so you can hear aided at 25db or better so you understand the most speech and hear the most sounds?

In theory, it is possible amplify full gain at the hearing threshold. But in practice, that is in hearing aids, soft gain also affects the amplification at higher levels because hearing aids cannot adapt fast to changes in level. Therefore, amplification will be too high for a short period of time when the level of the sound increases suddenly from being soft to being louder. In short, hearing aids cannot track the level perfectly and thus cannot apply correct amplification in every instant of time. This is why hearing aids work better with slowly fluctuating sounds, e.g. slow music.

What if the hearing aids are in compression all the time? Can they still not track the sound level? I can’t hear any sudden peaks, but I’ve wondered that can there be something so short that it’s not possible to notice it.

Kind regards,

Leia

Hearing aids have problems with measuring the level of the input sound for sudden and short sounds, because the level is estimated with a time-weighted method.

Therefore, I think other methods are used to deal with the compression of sudden sounds.

I wish I could learn more about how Phonak’s hearing aids are doing that kind of things. I’ve been considering to trial microPower at some point, because I have a slowly progressing hearing loss, and because I’m curious how low frequency soft sounds would sound with it. (And microPower because it’s compatible with my favourite remote control Soundpilot2, and I’m not looking for wireless functions.) Does anyone know in what way or with what method does it handle sudden loud sounds? My high frequency hearing is quite sensitive to loudness.

Kind regards,

Leia

A persons Dynamic Range of hearing is defined as the amount of sound in decibels that they can hear without discomfort or distortion. Normal range is on the order of 100db (SPL) and a person with hearing problems could be much less than half of that.

A vast majority of top line aids on the market use WDRC (Wide Dynamic Range Compression) to handle the decreased dynamic range of those with moderate, severe, and profound losses.

Persons with these sensitivities of loss can only comfortably handle a limited amount of loudness from soft to loud because of damage to their hearing system called Recruitment).

WDRC aids are adjusted so that when the incoming sound reaches a certain loudness, called the Knee Point, the louder sounds are then amplified on a non-linear basis…meaning that softer sounds get more amplification than louder sounds.

It does take the aid a short but finite time, one to ten milliseconds, for the aid to determine if the sound has reached this Knee Point (Attack time).

All aids on the market have some kind of final maximum loudness circuit to limit peaks. But these limiters will cause severe audible distortion if driven too hard. An occasional peak clipped will probably not cause noticeable distortion .

Wife calling gotta go…Ed

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@jchunter said:

X, you say the strangest things… Please post the evidence that “no one uses ADRO” Moreover, please explain how this is relevant to the topic.

lets list who does not use adro any more
Siemens
Rexton
Electone
AM
Oticon
Bernafon
Unitron
Phonak (i think they used adro but I might be wrong, i think their cochlear bionics did use adro) their new products does not
Starkey
Omni
microtech
Widex
Gn resound
Beltone
sebotek
vivatone (now part of the starkey family- audiosinc)
audion
audina

do you want me to go on…

Ed, I think you are incorrect in your definition.
The dinamic range is defined by two limits the threashold of hearing (the softest sound you are able to hear) and the thershold of pain (the loudest sound you could bear).

@Deaf123 said:

I read you have a mixed loss. What is your unaided/aided audiogram like and have the gains on your HAs been maxed out?

Yes, I average in the 40-50dB loss up to ~2K and then it drops into the 90+ range unaided. I’ve never had an audiogram done aided, it is not common practice to do so because as we discussed hearing speech is different then hearing beeps :D. Even at frequencies where my loss is 90+ dB, I find I do not set the gain higher then 40, I also keep my max power at 110-115, this is not really much of a dynamic range to try to fit into.

Now that see your audiogram I can see why you are frustrated. Knowing the difficulty I have with my areas of severe-profound loss, I would have to say even with a seasoned pro fitting you who has the patience of an angel you would be difficult to fit. I trust you are a candidate for an implant but have decided against?

Zafdor: You certainly defined dynamic range correctly…You have a technical background as I do. I thought I was saying the same thing trying to express it in a more layman’s language. Thanks for the correction. Ed

@zafdor said:

Did all of these actually use ADRO?

I thought the only one who used ADRO was one of the AH & one of the implant companies? Do you know if they still use it?

It would certainly be a slap in the face to the R&D organizations in the big companies if they decided to license a technology (ADRO) from a 3rd party. There is no doubt instruments have and will continue to improve, but there is still a healthy dose of hype in their marketing and “we’re using what everyone else is using” (by licensing 3rd party technology) really does’nt fit this model. There is also the matter of licensing fees, since ADRO is a patented algorithm.

Are you aware of any double blind studies that show instrument (or algorithm) X ouputforms instrument Y for hearing loss of type Z?

I never really read an article saying brand x is better than Y based on this study.
Some of the studies I have seen have very low sample size less than 40 or so…

I could be wrong… I suspect, Adro does not work substantially better than NALNL1 or DSL1 or whatever, otherwise It would have been popular.

I think you can buy NAL lincense for about $5 grand or so…
Perhaps, Adro charges more, who knows

@Deaf123 said:

This is a serious question and something ive been wondering for a while now. If a hearing aid gives you as much gain as your hearing loss, does it completely cancel your loss and therefore result in you being aided to 0db? Say someone has 70db hearing loss and wears a hearing aid programmed for 70db gain(which may not even be the max gain the HA is capable of!) would he have an aided score of 0db? If not, what could be the reasons?

The main reason here is the lack of understanding the difference between dB and dB SPL. Moreover, when it comes to dynamic range, it is also expressed in dB, like the amplification (gain) although they are “another kind” of dB . The “dB” is not a “normal” measuring unit, like foot or pound. The “dB” is a dimensionless unit, it is just a reasonable manner to express really huge ratios, like 60,000,000 to 1.

Decibel

The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a power or root-power quantity on a logarithmic scale. Two signals whose levels differ by one decibel have a power ratio of 101/10 (approximately 1.26) or root-power ratio of 101/20 (approximately 1.12). The unit fundamentally expresses a relative change but may also be used to express an absolute value as the ratio of a value to a fixed reference value; when used...

Sound pressure

Sound pressure or acoustic pressure is the local pressure deviation from the ambient (average or equilibrium) atmospheric pressure, caused by a sound wave. In air, sound pressure can be measured using a microphone, and in water with a hydrophone. The SI unit of sound pressure is the pascal (Pa). A sound wave in a transmission medium causes a deviation (sound pressure, a dynamic pressure) in the local ambient pressure, a static pressure. Sound pressure, denoted p, is defined by ...

@Deaf123 said:

How much of your loss is conductive? I wonder if you have cochlea dead regions in the high frequencies? This would explain why the gain and MPO are set so low. What would you recon you hear aided in the lower frequencies? 5db? 10db? Have you tried setting the gain higher and what happened? What are your speech discrimination scores and on what types of tests? You can check my blog here: http://deafdude1.blogspot.com

I just had my second revision stapedectomy in my left ear, so I am down to a 10bD conductive loss there. I am going to wait a few more months to stabilize before I even put an aid back in thatear. My right ear ranges 10-30dB for conductive loss. Your question on cochlear dead regions is a good one, I really do not know as I have never been tested for this. My loss is due to otosclorosis and I am not really familiar with dead regions. I do have severe tinnitus (70+dB) at about 3KHz and I always reconciled that it would be pretty difficult to get much hearing in this area even aided. I score 96% for discrimination at my MCL (80dB) unaided in my right ear despite having no pure tone scores better then 80 above 3KHz. I need to add my audiogram to my siggy!

As for setting the Amplification/MPO for people with severe and profound losses, I think this is the gorilla in the room. Assuming one can even get satisfactory results with 120+dB MPOs, there is no way this can be good for whatever hearing you have left. This leaves one with the unfortunate reality that in order to function you may need to do something that long term can lead to even more serious problems. I did try upping the MPOs /gains to get some highs into my noggin and found indeed that the sounds I could hear up there mostly reached the pain threshold. My instrument is ADRO based and Eds last comment got me thinking that this compression technology may be the reason I have the problem,

Lancaster: When I went to engineering school a hundred years ago, we were taught that db is a log of a ratio of two powers times 10 (or volts or Amps times 20) and db SPL is a measure of a real quantity reference a standard amount. 0 db being the minimum sound pressure power per standard unit area that a normal person can hear at a specific frequency. (log to the base 10 not Naperian) Right? Ed

@zafdor said:

I just had my second revision stapedectomy in my left ear, so I am down to a 10bD conductive loss there. I am going to wait a few more months to stabilize before I even put an aid back in thatear. My right ear ranges 10-30dB for conductive loss. Your question on cochlear dead regions is a good one, I really do not know as I have never been tested for this. My loss is due to otosclorosis and I am not really familiar with dead regions. I do have severe tinnitus (70+dB) at about 3KHz and I always reconciled that it would be pretty difficult to get much hearing in this area even aided. I score 96% for discrimination at my MCL (80dB) unaided in my right ear despite having no pure tone scores better then 80 above 3KHz. I need to add my audiogram to my siggy!

You can Google cochlear dead regions. I also have posted articles on that in this forum. Nice speech score, you have normal hearing with HAs! Well not the annoying high frequencies. It’s been shown in lowpass filter speech that if you can hear well to 2000Hz, youll score 90% speech(monosyllabic words)!

As for setting the Amplification/MPO for people with severe and profound losses, I think this is the gorilla in the room. Assuming one can even get satisfactory results with 120+dB MPOs, there is no way this can be good for whatever hearing you have left. This leaves one with the unfortunate reality that in order to function you may need to do something that long term can lead to even more serious problems. I did try upping the MPOs /gains to get some highs into my noggin and found indeed that the sounds I could hear up there mostly reached the pain threshold. My instrument is ADRO based and Eds last comment got me thinking that this compression technology may be the reason I have the problem

I for one can’t get good results much above 500Hz. I think that has to do with cochlear dead regions. My ability to understand speech doesn’t increase with gains/MPO above 500Hz or so. I do wonder if high MPO(like 130db) HAs are what eventually wiped out what little mid/high frequency(100db HL) hearing I had. Oh well, less MPO would not have let me hear the mids/highs anyway so I might as well have enjoyed that hearing. Ill get it back soon with stem cells and more. How well do you hear the lows? Could you be getting more gain still?