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Newbie Comb Filtering Question

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I have moderate hearing loss around 2,000 Hz and got my first pair of hearing aids last week. I’m noticing an effect that sounds like I’m listening through a tube (or seashell). It’s most noticeable with background noise like traffic noise or water running through a tap. After googling I discovered it is called “comb filtering” caused by the millisecond processing delay of the hearing aids.

I have some Costco Kirkland 10s with tulip domes.

For people who had the same problem what did you do to resolve it?

I get the impression that the only option I have is to get some other aids like Widex Moments that have a very short processing delay.

This video around the 8 minute mark gives a good example of what comb filtering sounds like

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Well, I’ll tell you that I hear just about the same as your example, especially with traffic noise. I still haven’t fixed that. I have a pair of Resound ONE 9 Hearing Aids.

Bear in mind that you’re new to hearing aids and you’re probably using an open dome, which exacerbates the comb filtering effect. Also, hearing aids are aids that helps amplify what you don’t hear and, in doing that, there are side effects. That is: they introduce distortion to your hearing in hoping that the downside (distortion and somewhat unnatural hearing) is less than the upside (understanding speech).

Believe it or not, you will become used to that distortion.

My advice: Be patient and tell that to your audiologist. If possible, show him/her the youtube video.

Interesting video! Thanks for sharing @john_jobson.
I was always wondering why the -industry says that a 1ms delay is acceptable. That means, we have a 180° phase shift at a 500Hz tone. The result is going to be eliminated if both signals are the same strength, leaking + amplified signal.
Maybe it is because the standard ski slope loss only needs amplification for higher frequencies?
It would be interesting if you could share your .

Anyway as I understand it, the Comb Filtering effect might be reduced if you use closed fitting, f.e. power domes instead of open domes.

But I have another theory of what the problem might be: the “speech in loud noise” program builds a directional microphone. This is done by building a microphone array, adding the 4 microphone signals to one single mono signal. Thereby the directionality is lost and you hear the person in front of you louder.
It is mentioned in the video that adding the stereo channels to build a mono signal could cause the comb filtering effect. Actually, I think I can hear what you describe when I switch manually to the focussed program. I do not find it troublesome in real loud noise.
Maybe you can try this yourself? If you find this is the root cause in your case, the fitter can increase the level when autosense switches program to “speech in loud noise”.

Edited

Thanks for the replies. My understanding is that tulip domes are basically - once you stick them in your ears the 2 “petals” overlap so there are no open slits.

I’m using the Easy Line app usually in “automatic” mode when I’m outside, so maybe it is defaulting to the “Restaurant (noise)” mode. I’ll try to set it to the music mode today and see if that makes a difference for the traffic noise.

I guess my loss is really centered around 1.5k Hz. The “comb filter” sound is more pronounced in my left ear (blue line below), so maybe there is something my audiologist can do to reduce it when I see him next week.

From the video I thought it was kind of interesting that as he adjusted the time delay the pitch of the “comb filtering” effect changed. As the time delay increased it sounded like you were listening through tubes of increasing diameter.

image

Possibly not the best solution, but you can try reducing the amount of the effect (turn down noise reduction or try a different algorithm, or different settings of the one you are on). It’s going to be tricky unless you can tweak the settings in the environments that bug you the most. Your audiologist might have some audio samples that you can test with in the office.

Well, I have to thank @john_jobson because I didn’t know what was causing my discomfort. It was comb filtering on road traffic noise! So I disabled all gain on my lower frequencies /which I can hear normally, as my shows) and that ghostly echo disappeared. On my Resound ONE it was necessary to reveal all gain handles to do so.

But since you’re a new hearing aid wearer, I’d suggest you to get used to your hearing aids, and then start the fine tweaking.

Edited

When outside, the effect happens the least in Easy Line “Automatic” program and is obvious in all the other programs (Restaurant/Music/TV).

I also clued in this week that I could judge how good my hearing aids sounded by playing a piano video on my phone straight to my hearing aids (using bluetooth), and then comparing that to the video chromecast to my stereo and played through my Sennheiser HD 800s. The sounded thin, tinny, and I noticed a lot less piano reverberation. I figured just a single piano was easiest to compare the sound for instead of a full band.

I guess hearing aids are “communication tools” rather than “hearing tools”.

@john_jobson said:

I also clued in this week that I could judge how good my hearing aids sounded by playing a piano video on my phone straight to my hearing aids (using bluetooth), and then comparing that to the video chromecast to my stereo and played through my Sennheiser HD 800s. The HAs sounded thin, tinny, and I noticed a lot less piano reverberation. I

There are numerous post on this site for tuning your aids for music, but they’ll never sound like a pair of Sennheiser HD 800s!

To be anywhere near successful in streaming music, you need a dedicated music program, and lots of bass boost.
You need , or better yet, custom earmolds with vent plugs.

Just remember, hearing aids can’t amplify frequencies below 125 hz.

It’s all in the acoustics you create with the ear pieces.

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