XPost: comp.misc   
   From: trevor@home.net   
      
   On 25/04/2017 5:29 AM, Michael Black wrote:   
   > On Tue, 25 Apr 2017, geoff wrote:   
   >> On 24/04/2017 7:45 PM, Trevor wrote:   
   >>> Secondly if we are to take your statement literally then nobody   
   >>> should wear ANY hearing aid for fear of damaging what is left of   
   >>> their hearing at any frequency!   
   >>>   
   >>> I'm surprised people bother to make these comments without   
   >>> knowing anything about hearing aids.   
   >>>   
   >> And despite me making no claim to know anything about audiology ,   
   >> it would still vastly surprise me that the simple remedy for a loss   
   >> at a particular band is solely to boost the shit out of that band.   
   >> 14k, 8k, 3k, or whatever.   
   >>   
   > What I remember is that the ear has two or maybe more levels of   
   > nerves to detect sound, because otherwise the ear would be required   
   > to handle too wide a dynamic range. I'm not sure how that translates   
   > to loss at higher frequencies, but from what I was told, one could   
   > lose the ability to hear low level sounds, but still hear loud sounds   
   > fine.  This was decades ago, and maybe it was a simplification for   
   > "the layman".   
   >   
   > I don't think you can boost the high frequencies by too much, and   
   > expect "perfect" hearing.  One has to live with something in between   
   > "original" and bad hearing.   
      
   For many people the ability to hear above a certain frequency is lost   
   completely, or close to it, and no amount of gain would help. But   
   hearing aids are designed to cover the voice frequency range, and rarely   
   go past 8kHz anyway. Fairly high boost in the 2-8kHz range is not that   
   uncommon for those with simple high frequency loss. But *NO* hearing aid   
   will give a user "perfect hearing", only something more useful perhaps.   
      
      
   >   
   > Someone mentioned their parents or grandparents getting used to   
   > hearing aids, and giving up. Apparently that's common, one adjusts to   
   > what there is, so hearing aids can take time to adjust to. So I   
   > assume people adjust to the level of improvement that a hearing aid   
   > can offer.   
   >   
   > The electronics don't or didn't provide the same level of dynamic   
   > range as regular ears, so AGC, automatic gain control, kicks in   
   > somewhere in hearing aids, so that's another thing one has to adjust   
   > to.   
   >   
      
   Actually the aids themselves can easily cover the ears dynamic range at   
   very low gain, however if you have say 60db loss, maintaining 100dB   
   dynamic range would require a peak SPL of over 160dB! Not something   
   anybody could tolerate even IF the aids could manage something remotely   
   close to that. Fact is very loud sounds still sound loud to most hearing   
   aid users so the dynamic range provided must be restricted if they are   
   to hear quieter sounds at all.   
      
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