Re: [Phys-L] non-linear ears.

[Brian Whatcott <betwys1@sbcglobal.net>]

 Dan's suggestion seems like a useful improvement on the low pass filter idea: how about a Q-damper of the (high frequency) peak of the small Helmholtz resonator?Removing the porous plug would promote the high frequencies so helpful in decoding the sibilants and plosives.Highly testable, of course!
Brian W    On Saturday, November 14, 2020, 11:58:37 AM CST, Dan Beeker via Phys-l <phys-l@mail.phys-l.org> wrote:  
 
 “There was a porous white cylinder in the plastic tube between the aid and the tubing to the ear mold in my system.  I thought it was a liquid block.  Not!  But A low pass filter! “ 

Sounds like your hearing is not so bad. Be thankful. 

Pure conjecture on my part but the white cylinder may also work as a wax trap. The hearing aids really don’t like gooey substances on their “loud speakers”. I don’t have the molded type ear piece. My aids have a small white plastic cap with a small hole through it. When the hole gets clogged I hear absolutely nothing through the hearing aid. I would take them to the audiologist who would clean them and give them back saying there was nothing wrong with them. Never once was I told what the problem was.  I’ve since learned when my hearing aids don’t make a sound to check the wax trap. After removing the wax trap, a small 36 gauge wire poked through the trap usually does the trick. And I suspect you are likely correct that it also forms a low pass filter. Since there is little benefit from hearing high frequencies (from a conversational point of view), limiting high frequencies means the sound you do hear has less noise and more audible information content. If you have really severe hearing loss this might be quite beneficial. 

As a related point of interest, have you ever noticed the felt pad over the hole in an electret microphone? It serves as a filter to reduce high frequency peaking, flattening the response curve of the microphone. It, along with the volume of the cavity (think Helmholtz resonator), shape the primary response of the microphone. I suspect much the same happens in hearing aids.

Dan

Date: Fri, 13 Nov 2020 18:46:16 -0800
From: bernard cleyet <bernard@cleyet.org>
To: "phys-l@phys-l.org" <Phys-L@Phys-L.org>
Subject: Re: [Phys-L] non-linear ears.
Message-ID: <BACFFE09-4D7A-475C-B71B-E9083607ACD6@cleyet.org>
Content-Type: text/plain;    charset=utf-8

> On 2020/Oct/30, at 08:29, Paul Nord <paul.nord@valpo.edu> wrote:
>
>
> What's interesting is that the standard hearing test you might get from a
> doctor only goes up to 8 kHz.  They apparently don't consider hearing loss
> above those frequencies to be important.
>
> Paul
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Which angers me.  

There was a porous white cylinder in the plastic tube between the aid and the tubing to the ear mold in my system.  I thought it was a liquid block.  Not!  But A low pass filter!  I removed it and now can hear clock ticking and other high frequency sounds.  Also, tho the majority of voice is below 8k Hz, I?ve found a little better comprehension W/O the filter.  

bc  ?  being an amateur horologist, is pleased;  likely can now hear crickets, also


Project:  Use the recently acquired Vernier sound sensor and Logger Pro?s included FFT to characterize clock ticks.


------------------------------


Dan Beeker

PureUnobtanium.com
Indiana University - retired


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