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Ear-Mold Vent Size vs. Sound Clarity

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When I bought my Phonak Savias, I requested the vent in the ear mold be made slightly larger for a special purpose. We thought this would be okay as long as the larger vents did not cause feedback. However, speech discrimination and sound clarity in certain environments seemed to be lacking. Over a period of three years we made many attempts to adjust compression, volume, etc, to improve performance. Increasing volume did not improve speech discrimination. Also, the aids did not work with my cell phone. It was impossible to determine if the problem was with the adjustments, or a problem with the aids. I thought possibly my hearing was deteriorating and nothing could be done. When an additional increase in volume did cause feedback, the audiologist suggested we reduce the vent size to factory specs. Like magic, clarity and speech discrimination returned. I could now for the first time use the aids with my cell phone. The processors had sacrificed sound performance to prevent feedback. Is anyone else experiencing this?

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We experimented with vent sizes (both the physical vent size) and the fitting software vent size on my wife’s Oticon Epoqs. What worked best for us was a large physical vent size in combination with a different (smaller) software vent size.

I forgot what software vent size we ended up with. But it sounded better with a software vent size that was different from the large physical vent size.

Here’s a link to a post in another thread. Click -> HERE27.

Errr … so the aids worked well when set up as recommended by the software?

But they worked badly when you (incorrectly) increased the vent size for a ‘special’ reason?

By doing this you lost bass volume due to the vents and possibly treble volume due to the feedback manager trying to prevent feedback.

I’m probably stupid - but I’m not sure what you are trying to say in your post.

I am not familiar with adjusting the “vent size” with fitting software.

I had the physical vent size increased slightly so I could insert a plastic audio tube from an aviation headset. The point being that the increased vent size caused the aids to perform poorly. Since there was no feedback, I didn’t realize initially that the aids were performing poorly and therefore that the increased vent size was causing the problem.

@dungsiabc said:

You are true! Too larger vent makes poor hearing. I use 2 Phonak Savia 311 too.

The original vent size on my Savias was 2mm. The problem occurred when we increased the gain. As we increased the gain, volume increased, but clarity decreased. We reduced the vent size to 1mm and the clarity returned.

In reply to @dungsiabc

@dungsiabc said:

You are true! Too larger vent makes poor hearing. I use 2 Phonak Savia 311 too.

I would not say this is always true. The vent size should be selected based on your hearing loss. If the vent size is selected appropriately & the hearing aids are programmed to take the vent size (software vent size) into account things should be ok. There is always the danger of letting too much sound escape from a overly large vent, this will result in reduced low-frequency gain as well as increased feedback (which generally reduces available high-frequency gain). Newer products are equipped with more advanced feedback management that should allow for more gain with less feedback and thus larger possible vent size. The clarity issue becomes large when vent size limits gain for soft high-frequency sounds which allow sounds like “s”, “f” or “sh” to be audible.

Conversely a vent size which is too small will result in over-amplified low-freqeuncies and what we refer to as the occlusion effect. This results in hearing our own voice in an abnormal way (usually described as a “boomy echo” or “hearing in a tunnel”).

I had ear molds with a small vent. I went to a different audi for tuning and he made the vents larger, making sounds more natural and I felt I could hear better. He lowered the compression which helped with the clacking of the keyboard and paper rattling.

I broke part of a mold and today saw my original audi who said lets try a (ear cone shaped thing). It increased feedback which he adjusted and is ok for now.

I’m not sure what vent size does or doesn’t do, but I know it does make a difference.

In reply to @Stratuscom

@Stratuscom said:

The original vent size on my Savias was 2mm. The problem occurred when we increased the gain. As we increased the gain, volume increased, but clarity decreased. We reduced the vent size to 1mm and the clarity returned.

According to your hearing diagram, I believe that your Savia with 2mm vent work very bad in noisy environment even in calm. You might sometimes couldn’t hear someone talking when they sit very near you. You should accept some occlusion with 1mm vent.

In reply to @OldLincoln

@OldLincoln said:

I had ear molds with a small vent. I went to a different audi for tuning and he made the vents larger, making sounds more natural and I felt I could hear better. He lowered the compression which helped with the clacking of the keyboard and paper rattling.

I broke part of a mold and today saw my original VA audi who said lets try a (ear cone shaped thing). It increased feedback which he adjusted and is ok for now.

I’m not sure what vent size does or doesn’t do, but I know it does make a difference.

According to your hearing diagram, you should wear a mold with 3mm vent.

In reply to @Kadougan

@Kadougan said:

Conversely a vent size which is too small will result in over-amplified low-freqeuncies and what we refer to as the occlusion effect. This results in hearing our own voice in an abnormal way (usually described as a “boomy echo” or “hearing in a tunnel”).

Sometimes we must accept some occlusion. Because, if you want feel total free of occlusion, you won’t hear well with .

Edited

In reply to @cjpines

@cjpines said:

what is a vent size?

There is this excellent review article cited by MDB in 2017 on the effect of venting. Towards the end of the thread I more specifically include a link to one of the papers on which the review is based, a 2006 Widex technical paper that has a graph of a group of mildly sloping high-frequency hearing loss subjects that were tested with CASPA3 words in quiet at a 30 dBHL level. Word recognition scores decreased 30% with increasing vent size.

NOTE: The original link that I provided to the WidexPro website seems to be broken (Widex locked the door except for registered providers only?). I have added another post with a link to a publicly accessible version of the 2006 paper to the thread cited below.

Article on open fit vs closed fit

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