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Binaural fitting with four microphones

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Edited

Can someone explain in somewhat technical terms what additional advantage is gained with fitting involving 4 mics (2 per ) in terms of beam forming vs monaural fitting?

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I googled it. Lots of tech information available for you to read, basically 4 is better then..2

“ fitting with four microphones allows for more precise adaptive directional beamforming and a wider spatial understanding of the environment compared to monaural fitting”

Why.

“Because synchronizing the signals from all four microphones, a more advanced and spatially aware microphone array is created, resulting in unparalleled performance in distinguishing speech from background noise”

thanks tenkan. Yes, marketing statements like the one you quote are abundant. Hoping one of the can chime in with a more technical explanation

It has more to do with where the microphones are rather than how many there are, which is why they are typically referred to as “directional microphones”. When there are two microphones, specifically one in front and one in back, the hearing aid can determine which direction sound is coming from due to timing differences. This is how hearing aids are designed to help the user have better focus on sounds coming from the front. It is shown in research that directional microphones are beneficial for tasks of understanding speech in noise.

In reply to @ed243

@ed243 said:

Yes, marketing statements like the one you quote are abundant. Hoping one of the AuDs can chime in with a more technical explanation

Too much for me but try these, not sure how much more technical you need.

The Benefit of Bimodal Hearing and Beamforming for Cochlear Implant Users2

Cochlear implantation is the standard treatment for severe to profound hearing loss. While cochlear implant () users can communicate effectively in quiet environments, speech understanding in noise remains challenging. hearing, combining a...

https://www.researchgate.net/publication/322229992_An_Evaluation_of_Hearing_Aid_Beamforming_Microphone_Arrays_in_a_Noisy_Laboratory_Setting1

In reply to @ed243

This is where you start getting into processing i.e. two hearing aids working together. If you are just getting a single hearing aid this does not really matter. When you have a set of hearing aids, now it’s more than just front/back, but the hearing aid processing will try to detect right/left as well.

Edited

In reply to @PaulC

I have a question for you as an audiologist. While I love my Oticon INTENT1 aids, the one thing I find missing is the fact that when I wore the older Oticon aids I felt like I had better sense of direction either with ITE aids. But I didn’t have as good of word recognition with the older aids.

Am I right that because the aids were in my ears that helped me with direction more than when the microphones are behind my ears.

In reply to @ed243

That would be my thinking. The less-processed sound coming through dome vents will be unaffected by the more-processed sound coming from the hearing aids themselves.

In reply to @cvkemp

This is where it gets less concrete. Because hearing aids are worn within the concha, the hearing aids themselves benefit from a pinna effect i.e. the pinna opens forward and thereby “rejecting” sound from the back. However, half shell and full shell ITE hearing aids typically have directional microphones as well, so you could have been benefitting twice, once from the hearing aids and once from the pinnas (pinnae?).

Edited

I had this same question and actually I didn’t want any technical explanation, so I’ll just tell you what it sounds like. I have no eyesight by the way so I pay a lot and I do mean a lot of attention to how my ’s sound.

I used 2 types of hearing aids from phonak, both called Virto. The titaniums have a single omni mic each and sit deep inside the ear. The Virto rs, sit a bit further out of the ear and have 2 mics each.

With the single mic in each ear, I got good directionality and spacial sound awareness given they were sat so far in my ear, but, I had no way to control the levels of sound around me. If I sat in a noisy room and was talking to someone in front of me, the people behind me were just as loud, if not louder.

Noise supression in order to hear speech better was good with the single mics but again, it blocked out all noises including sometimes things in front of me that I wanted to hear.

With the 4 mics making 2 beams on the Virto Rs, the horrendous chatter behind me can be turned down. My brain doesn’t have to think so much about focusing on what’s in front of me. When I use noise block, I can tell the aids either block all around me, or block the back and focus on the front.

When you have good hearing, your brain automatically zooms in on what you want to hear. When you don’t, you have to get tech to do this for you. In my mind this wasn’t logical and the 2 omni mics should have worked. All I can tell you is that whilst they work in some situations very well, get a complex noisy environment and it all falls apart :slight_smile:

Try researching Phonak white papers on their pro website. I’m sure there will be something about this although I’m not convinced it will answer your experience.

The combined information from a four microphone array (two microphones on each aid) allows for a narrower microphone focus directly in front of the person which can improve the signal to noise ratio for talkers immediately in front of you more than would be the case if two pairs of microphones were working independently on each ear.

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