Re: Elecraft Digest, Vol 20, Issue 22 Headphone for hard of hearing

[JohnChanceRead]

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 ?.  Any  suggestions would be most welcome.
John G4BOU
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[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.

[hidden email] 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
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[Vic K2VCO]

[hidden email] wrote:
>  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 would be worth a try to take a small speaker and cut four pie-shaped
segments from the cone, leaving four strips about 1/4" (6.4 mm) wide to
hold the voice coil in position.  You might also try something like the
zero-beat indicator that's been discussed here to give a visual
indication of correct tuning.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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[Sverre Holm-2]

> -----Original Message-----
>
> 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.  

It occurred to me that the vibrator which is found in most cellular phones
these days may be just as suitable for feeling the vibrations.

Anybody who has any experience with such a device?


73

Sverre
LA3ZA
http://www.qslnet.de/la3za/
 

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[David A. Belsley]

John:
   Do not cut the speaker cone.  It serves two positioning purposes.  
First it holds the voice coil in place so that it does not rub  
against the magnet or driving coil (depending on the speaker type).  
Second it provides the spring that allows the coil to return to the  
center of its travel from either direction.  Cutting the cone  
material would seriously compromise both of these actions.  I would  
think that an earphone module would serve your purposes quite well.  
They would make some audible sound, but it wouldn't carry very far.

best wishes,

dave belsley, w1euy


On Dec 22, 2005, at 6:41 AM, [hidden email] 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 ?.  Any  suggestions would be most welcome.
> John G4BOU
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
>  http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com

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[Nick Waterman]

Sverre Holm wrote:
> It occurred to me that the vibrator which is found in most cellular phones
> these days may be just as suitable for feeling the vibrations.

Doubt it. They're basically an electric motor with an offset weight.
I'll admit I've never tried feeding them with AF AC, but I wouldn't
expect them to respond well or give much indication of different pitches.

You might do better with some sort of solenoid?

> Anybody who has any experience with such a device?

Yup, I work for a well known mobile email gadget company, and have taken
quite a few of them apart   :-)

--
"Nosey" Nick Waterman, G7RZQ, building k2#5209.
#include <stddisclaimer>    [hidden email]
Sign in a taxidermist's window: We really know our stuff
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