[Elecraft] Headphone for hard of hearing

[David F. Reed]

John, you bring up a very interesting issue here, and there are a world 
of possibilities.

Speakers in general are transducers that convert electrical energy to 
motion; the motion of the speaker coil moves the cone it is attached to, 
which moves the air, which is what we hear or feel. So, more motion 
(easier to feel) usually means louder for them too.  Your idea of trying 
to remove the paper (speaker cone) could be a good one, if you can 
adequately sense the motion to decode the tone.

I am curious though, how do you achieve zero-beat?  If you are using an 
optical aid, such as some we have seen discussed on this list, what of 
the idea of visually decoding the morse?  Most navies did this for 
decades for inter-ship radio silence, and should prove inoffensive to 
the neighbors as well.

Another question, is can you feel the sound pressure of headphone(s)?  
Efficient headphones (high sound pressure for a given drive level) have 
been discussed on list as well, and if that works for you, it might be a 
way to go; one option might be from the Clansman series of UK army 
radios, some of which use bone conduction of sound to get it to our 
ears; odd looking setup that places the speaker on the rear of your 
skull, but it may work as well.

JohnChanceRead at aol.com wrote:

>I am interested in determining which earphone (or speaker) would have the  
>highest physical movement.  I am deaf and intend to read morse by feeling  the 
>vibration.  Once I have found the earphone/speaker, I then have another  
>problem.  I suspect I will have to find the K2's best audio that fits  the device, 
>then I need to nullify its audio output, since I do not want the  neighbours to 
>be annoyed by loud morse noise.   I partially  understand how a speaker works 
>and in order to decrease its audio  output I will have to remove or partially 
>remove the paper which joins  the core to the outer body - but will it still 
>vibrate ?.  
>
It should still vibrate (since its the audio driving the coil that moves 
the paper cone), but might be sub-optimal; worth a try if you can find a 
cheap speaker with a blown cone - a possible source would be the custom 
sound installers for cars; they rip out the old speakers and generally 
discard them, so it might be a free source.

>Any  suggestions would be most welcome.
>John G4BOU 
>
If you like the idea of visually decoding it, the tool for visually zero 
beating might be usefully adapted to do double duty as a "morse 
indicator" as well.

Please let us of developments; we might be able to help more.

73 de Dave, W5SV