Great! Now I only have to identify the adapter from BTE to slimtube: the Grip tip is apparently an alternative to a dome.
The issues with playing musical instruments usually seem to come down to the feedback suppression methods used by the aids. They need to be turned down or even turned off. The aid you have selected seems to be a very high power aid intended for those with a profound loss. Yet, you have a moderate-severe loss. It seems to me that a lower powered RIC aid would be sufficient for your loss, while providing better audio quality. Signia and others have special programs for those playing a musical instrument. You could benefit from a custom mold though, and they would help with the feedback issue, possibly allowing suppression to be turned right off for the music program.
@Sierra Thanks for your remark. I now have the Bolero SP, which is also for more severe hearing loss. However, I found that it is better able to handle the piano than the OPN1 RIC was. I speculate that is exactly because the receivers can handle more sound.
Still, I will check the fitting range and recheck the range for the Bolero SP for comparison.
@Zebras I am still wondering what the bit between the body and the slim wire is and where I can get it. Any thoughts?
This is how your loss fits within a M (medium) powered RIC receiver fitting range.
And this is what the First Fit gains would look like with this M receiver and a custom mold with 2 mm vents. You may get away with closed click sleeves, but at least in the computer custom molds would be safer from a feedback point of view.
I’ve just looked at the places where I get supplies in the UK and they don’t sell them. When I was struggling to find supplies, I emailed a few people on eBay. Might be worth you doing that?
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@Sierra The fitting range from the technical specs for the OPN1 BTE:
The fitting range for the Bolero SP B90’s with my current audiogram taken from Phonak’s Target software:
Comparing the two I see that the OPN1’s fitting range is 10dB higher than the Bolero SP’s. My audigram falls in the middle of the Bolero SP’s and just above the middle of the fitting range for the OPN’s.
Comparing the OPN1 to the OPN1 RIC with a 85 receiver:
The 85 has some very soft sounds, which I won’t hear anymore, however it can generate sounds between 20 and 30 dB like my Bolero SP’s which the OPN1 BTE can’t. Question is whether I will ever be able to hear those sounds…Looking at the fitting range of the 105 receivers of the RIC in the specs, I see an identical fitting range as the BTE’s.
So indeed I would rather have the RIC’s: They allow me to switch receivers. Any idea what a reasonable rate for second hand OPN1 RIC’s’? What is see is somewhere around 900$ for a pair. Seems a bit steep, but those could be the ones that aren’t sold. 
@Zebras I just emailed two of my local suppliers whether they would be able to deliver those thingies to me.
It seems to me there is no value in having hearing aids that are much more powerful than you really need, other than providing margin for a very significant deterioration in your hearing. Typically what I see is that the more powerful the aid or receiver, the higher the total harmonic distortion. The high frequency bandwidth is also often limited. Those seem to be the price of getting more power. You have reasonably good high frequency hearing, so I would not write off hearing the highs.
Price is another matter of course. Seems to me that the BTE’s would work for you, but perhaps not ideal.
If you are not actually using high power, the THD may not be as high as the spec. For a “high power” receiver, more likely they turned up the sound output until the THD number looked bad, turned down a few dB, and wrote that on the spec. THD typically falls at lower sound output.
Yes, a basic compromise in ‘speaker’ design is good output to high frequency or BIG output at mid-high freqs. Mechanical things don’t like to move fast. A lighter armature will vibrate fast but not strong. A heavier armature has more output in mids but trades-off the highs. For speech, mids-highs are critical. I agree Markismus’ flat curve and love for music suggests an extended top-end.
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I am starting to be convinced that this may not be the best acquisition.
What I am wondering is whether the Phonak Bolero B90 SP’s wouldn’t have this same problem. I agree that I am still looking for better hearing aids, so they aren’t perfect.
I hear what you are saying. My guess would be that when they use the same RIC hearing aid but switch out the receiver only to give more power, they must be doing it by lowering the impedance of the receiver. That will draw more current from the amplifier in the aid. I guess the question is what impact will that have on distortion. Unlike a lot of audio equipment, they don’t provide that kind of detail. It does beg the question as to why they supply Standard, Medium, Power, and Super Power receivers all using the same aid. If there was no advantage to the lower power units why would they supply them?
Here you are:
There is a specific adapter and thin tube for power aids. I have an Oticon mini BTE and have both and ear hook and thin tube amongst my spare parts.
It’s late here but I’ll try answer definitively tomorrow when I’m wide awake.
Alternatively, contact that website - they’re pretty knowledgeable.
Your audiogram isn’t a million miles away from mine. You’ll be ok with thin tubes.
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@davart Thanks!
I can’t find the technical specs of the mini BTE. I can’t seem to find them in Genie2.
I only find the Siya BTE and the Alta2 miniBTE which have a 85 receiver. I see the word Synergy on your HA’s. Are Oticon Spirit Synergy Mini hearing aids the right ones?
In the case that your HA’s do have 85 receivers, that would support @Sierra 's argument, instead of repel it. So I am still in a quandary…and the meeting is planned for this afternoon…I think I am going to shower first!
What is the difference between the OPN mini BTE and the OPN BTE PP13?
Everyone thank you for the support! It is much appreciated. I decided not to buy these OPN’s.
To get “more!” out of a ‘speaker’, we have two choices:
- more electrical power to the speaker
- a speaker which makes more sound from electrical power
HAs call the speaker a receiver, and it is a very specialized thing, but does not break any laws of physics.
And there are dozens of receiver models to cover a wide range of needs. High power, extended bandwidth, ultra-tiny, even crude+cheap.
It does seem that “high power” receivers often go for lower impedance to suck more from a fixed battery voltage. But that hurts battery life. In general low impedance raises amplifier THD, but with B or D amplifiers the amp THD should be insignificant.
Speakers all have THD distortion, rising with level. The balanced armature receiver has some extra sources of distortion but the designer can work with proportions, size, and specs to deliver astonishing high clean levels to an ear.
Speaker/receiver acoustic output per electrical Watt, efficiency, can be good at low frequencies but always falls-off at high frequencies. Take receiver 17A003 as typical. If the iron in the armature is increased (red), the added iron in the varying magnetic field will produce more Force and higher output. However the higher Mass shifts the resonance(s) down and there is -less- output at higher frequencies. A lesser mass of iron (green) gives less output at low freq but vibrates better at high freq.
(In real receiver line-ups it is unlikely to find this simple relationship because other parameters may be tweaked.)
So it really matters “why?” we want “high power”. If it just has to sound louder, clarity not critical, the red curve makes the most of the power. This is also good for severe loss 100-1000Hz and “no hearing” (don’t even try) above 2kHz (many “power” users may be in this situation). For my ski-slope, I don’t want <1kHz and actually the stock '003 does best where I need it. For a musician with OK hearing to 4kHz but needing fine discrimination of 5k-10kHz cymbal and string-zing balance, the “green '003” light armature covers that area best.
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Why can’t the processor compensate if the characteristics of the receiver is known? I would think that an upper limit is indeed given with a given receiver.
However, the fitting range suggests that up to 9kHz the receiver is able to generate output up to even an higher power than at the frequecies below 750 Hz. If the fitting range holds and the characteristics are known, I just don’t see why the larger receiver should introduce more distortion.
What am I missing?
The only thing I see is that it won’t be able to generate soft sounds at high frequencies as well as less powerful receivers. So when I play a note, I suspect that it could start to warble when it dies out: Not being able to generate the full harmonics at lower volumes. Is this what is meant with harmonic distortions?
The electronics can add gain. They can’t force the speaker to make more acoustic power than it is physically capable of.
Yes, we can increase amplifier power, but at the cost of battery life. And the higher electrical power demands larger electric parts inside the receiver, a larger heavier receiver.
We say “harmonic distortion” because, in the simplest case, we put in say pure 1kHz and get out 1kHz 2kHz and 3kHz. Yes, all real sounds have harmonics, but we do not want the amplifier or speaker to add more.
I understand that we don’t want to add more. We can compensate for the known added characteristics of a amp+receiver setup, though.
If we know how a signal is transformed by a setup, we can compute the needed input to generate the wanted output.
IIRC, if I have computed the needed output signal (O(s) usually in the Laplace domain) and I known the transfer function (T(s) also in the Laplace domain), I can construct an input function, (I think it was something like I(s)=[O(s)+T(s)]/T(s),) transform it back to the time domain and offer it to the amp. That way you get clear signals from receivers if you generate the sounds digitally.
You could construct an ‘analog computer’ that transforms the signal electronically to generate the needed I(t) from a wanted O(t), but it would be for a unchanging setup. I guess that is the reason why some amps sound awful with some speakers and great with others.
As the receivers of the Oticon can deliver up to 137 dB SPL at the high frequencies, it won’t be a matter of having too limited power.
Question that remains for me is whether the REM measurements can compensate enough for the changing setups with each different ear canal.
Lack in that department would explain why some people prefer Oticon, some Widex, some Phonak, etc., etc…
So if it is generally held that power receivers sound less for people with only severe hearing loss, it seems to me that some signal processing is not optimized: “Presuming every user has profoundly bad hearing that part remains constant.”
I really wish the info on these receivers was in the manual! I wish that next to the expert systems we could get at the backbone of the hearing aid programming. We really have a long way to go before it’s Christmas, I guess.
Yes, all that can be done. To correct frequency response in speakers and rooms we used equalizers, from hand-built analog to graphic analog and today usually digital. Distortion can also be corrected (or added!). In fact there is a thing “Amp Modelers” which is a smooth guitar amp and a processor programmed to emulate the response and distortion of many “classic amps”. 5 kinds of Fenders, 6 kinds of Marshalls, 3 Ampegs, 4 Gibsons, at the touch of a button.
Adding distortion is easy because most distortion is a “falling short”. The signal rises to what should be 24 volts, the amp can only do 20 Volts, we can easily replicate this smash-top wave on another amplifier with much more than 24V max output.
Cancelling distortion is much harder. In electronics there is much use of Negative Feedback which pushes the amp when it tends to fall short. But it will not increase the MAXimum output of the amplifier. I have a 148HP engine in my car. Pushing harder on the pedal, or putting a booster on the pedal, won’t get me to 200HP.
Yes; speaker systems generally do not cite the specific info we really need. There are/were some measurement issues: few labs really had the facilities and calibration to get numbers which would reproduce in other labs. Mostly E-V developed their speakers by comparing with a JBL in their test lab, before that JBL tested against Magnavox in James’ garage; relative numbers, not numbers you could publish. Much everyday HA work is done in unrealistic couplers because the really good couplers are costly and fussy.
And for most complaints of “clarity”, we do NOT want the MAXimum output. We want Gain at low and medium sound levels. Gain is more often limited by feedback. We can’t arbitrarily turn-up-the-gain: it will squeal. And it most often squeals around 3kHz, which for us ski-slope folks is critical to speech. Yes, digital dips and phase-shifts can allow more gain before squeal. It may be these algorithms that bother some people. Note that for music-only listening we are advised to turn-off anti-squeal and accept the lesser gain.
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Thanks your for reply!
Reading through the not-great paper on receiver MPO, I can’t help but feel that using a receiver with greater MPO is better. The reduction in size has a negative impact on receivers and the analogy with speakers falls short, because design restrictions that have nothing to do with optimal sound design drive their size beyond what is best for sound production.
However, I did spot this curve that clearly implied that receivers have a problem with getting enough SPL at higher frequencies:
The frequency curves in the technical specs of the BTE PP and miniRITE also drop off at higher frequencies. However, in the technical specs I can’t find frequency response curves for the different receivers for the miniRITE. It does show that the BTE PP with a tube outperforms the miniRITE everywhere, while the slimtubes and the miniRITE are both better at different frequencies.
It does give the total harmonic distortion for an input of 70dB SPL (which is also not informative for piano…). Oddly enough it only goes up to 1600Hz. But at 1600Hz the BTE outperform the miniRITE by 1%(!!) Yes at the lower frequencies the BTE has thrice as much distortion as the miniRite. But before it hits the speech area it is already better!
So it seems that my experience with the Bolero SP’s giving a less distorted sound for the piano than the OPN1 miniRITE is not as subjective as I would have thought.
All this is dependent on the technical specs of Oticon not differentiating between the receivers 60, 85 and 105, off course. I still wonder if someone has any info on the frequency curves of the receivers. The not-so-great article implies that the only difference between low- and high-MPO receivers is the point at which the can’t cope anymore. So also in that text there is no discussion on the frequency aspect.
Here is a couple of links to look at for Oticon technical data.
I suspect if you hunt around there will be specs for the other power levels besides 85, but here is a more general document that includes the 60, 85, 100, and 105 power levels.