Domes and feedback

Does the type of dome influence the amount of feedback you get? Right now I’m trialing the Oticon Agil Pro Minis with an open dome. I’m getting quite a bit of feedback in one ear. Before these aids I wore the Oticon Deltas with tulip domes and had almost no feedback. Is that, at least in part, a function of the difference between the two domes?

Yes, correct.

Yes, definitely the type of dome or mould does affect the amount of feedback. A mould or power dome will give almost no feedback, but closed and open domes both give varying degrees of feedback. This should all be taken care of by the feedback manager so that you do not actually experience feedback.

I find it a bit of a “Catch-22” situation in that those of us with high frequency losses do not need moulds or power domes to cope with the loss (no great amount of gain is needed in the low frequencies). However, the high gain we need in the high frequencies causes feedback so we need closed or power domes just to reduce the feedback.


So far I have not experienced the feedback manager kicking in that quickly. Unlike my old aids, the squealing goes on for quite a while. No one has suggested power domes for me. When I first purchased my Deltas we experimented with a closed dome. I found the mould and the occlusion very uncomfortable. But then, whatever feedback I had was minimal. (My hearing has not changed since then)

Try some Unitron Moxi 20s – I am trialing them now with open domes and they are incredible – just finished trial on Oticon Acto Pros and the Moxis blow them away in every respect…and are are about the same price as Acto Pros but equivalent in specs to your agiels… I used power domes on the actos and feedback was minimal but very uncomfortable compared with open domes, but using open domes on the moxis I can cover my ears with my hands with no feedback… just a tiny bit until they adjust – they are really incredible difference in sound quality and performance in my experience…

I haven’t heard much about the Unitrons on here. I’m wondering whether it’s a product many audiologists use.

Right now the feedback in my left ear is not acceptable. Once it starts it takes a long, long time to die down and when it does, it seems there’s a slight tone that lingers for almost a minute.

Since my hearing in both ears is pretty much the same, I’m wondering why one ear would have a problem and the other not. Also, I’m assuming that the reason I had no feedback to mention a few months ago when I wore the Agils, had to do with the programming. I too, love the open domes, very comfortable, but I could live with the tulip dome if necessary.

it could just be that the feedback canceller wasn’t enabled - you should be able to get away with open domes (but that also depends on the shape of your canal and whether you’re susceptible to excessive earwax). Unitron is a good company and I think there’d be quite a few audiologist who use them - but so is oticon.

Thanks for the input.Hope you’re right. I’m a low to no wax person with small ear canals. If Unitron Moxi would do what the Agil Pros do, I’d be thrilled financially :wink:

My delta aids used to feedback quite a bit and I ended up using power domes just to get rid of the feedback. I now use phonak audeo smart aids and use open domes with zero feedback at all. I put this down to better software by phonak but there may be other factors experts on these forums could point out.

generally speaking unitrons are older model phonaks. remember looking at the unitron aids they tend to have different features than the original phonaks that they are based off of.

YES! Tulips feedback less than full open but, at least for me, are still open and not occluding. I really like the tulip domes.

In order of feedback, from most to least:

open domes
tulip domes
closed or power domes
custom mold

Closed domes are equivalent to tulips, not power domes.