I generally hate when people start asking questions before they’ve
done enough research, but because my situation is, um, challenging,
I’m hoping some of you will have mercy on me and help spoon feed me
My wife suffers from a degenerative neurological disorder. It’s
guaranteed to only get worse with time. Besides the physical handicap,
she’s showing signs of dementia as well. Our house isn’t grand, but
it’s big enough and has enough corners and doors and whatnot, it’s
often difficult for us to hear one another between rooms. Further,
if she fell or something under just the wrong set of circumstances
(me in the shop with equipment running, for instance), I wouldn’t be
able to hear her call for help, no matter how loudly she called.
The main reason I’m writing here is that sometimes she gets confused
and it is really hard to do anything else when I have to keep running
back and forth to answer her questions. Also there is a safety aspect
here that I really can’t ignore. What I’d like to do is set up an
always-on home intercom. We can’t use something which requires her to
walk to a unit on the wall and push a button or whatever to contact me.
Both mentally and physically that won’t work, and it really won’t
help if she breaks a leg in a fall. Even a wearable fob wouldn’t work.
Dementia, remember? She needs to be able to just call out no matter
where she is, no matter what doors are open or closed, and I need to be
able to hear her well enough that I know what’s on her mind and be able
to respond to her. I can think of about a dozen places where I’d like
to put a microphone and a speaker. Many of them quite near each other,
yes, but again, I don’t want to have to worry about a door being closed
or something blocking her voice should she have a real emergency.
Yeah, I thought about baby monitors, but a) we both really want
something wired (would you want every conversation you have with your
spouse broadcast to the neighborhood?), and b) I’d have to buy about a
dozen pairs, they’d all have to work together, and since they’re really
not designed for that, I’d imagine feedback would be a real issue.
I could see that costing a lot of money and in the end, not working.
I looked into commercially available intercoms, but they are a bit
spendy, but more importantly, I couldn’t find one that works quite
how I’d like it to (I guess there isn’t a big market for the whole
always-on, hands free, any unit to all other units intercom thing).
To try to get what I’d really like, I’m thinking of using a couple
SheevaPlugs (en.wikipedia.org/wiki/SheevaPlug) or similar
networked together, each with a bunch of the cheapest USB audio
cards I can find (that’ll still do the job, of course) to handle
several microphone/speaker pairs on each system (again, the cheapest
microphones and speakers I can find that’ll still do the job).
I’m thinking with a setup like that, and with Asterisk running on the
plugs, I should be able to treat each of those USB audio cards as a
phone, make them all automatically dial in to a conference call at
system startup time, and we’d have a hands-free always-on whole house
(including shop and garage) intercom system.
If you don’t know and don’t feel like following that link, SheevaPlugs
are just fanless (also diskless and headless) fairly cheap little
computers that I can hide away just about anywhere. They have an
SD card slot, one USB port and gigabit Ethernet, and that’s about it
for expansion and I/O. I’d probably be putting Debian on them just
because that’s what I’m most familiar with.
Does anyone know of a reason why that won’t work?
Does anyone have a better idea?
Can anyone tell me what I need to be sure to look for in a USB audio
card? I know NOTHING about sound cards in general, and even less than
that about the USB ones. It’s just not something I ever got into.
Does anyone have any specific recommendations for any particular
hardware (audio card, microphone, speaker) that’s a particularly
I’m concerned about feedback. Is Asterisk able to keep nearby speakers
from feeding into nearby microphones, even ones that aren’t on the same
Is there a way to set a minimum volume threshold on the microphones?
I’d like to make it so you have to raise your voice a little so
various shufflings and mumblings we all make as we go about our day
don’t get transmitted, and as long as the TV is set down low, it
doesn’t get transmitted either. Certainly NOBODY wants bathroom
noises broadcast over an intercom.
What about noise cancellation? It’s not an absolute requirement, but
boy it sure would be nice to not have to mute the mic in the shop, and
just let the system filter out the noise from machines as I turn them
on and off out there. I can make do with a manual mute button, but
it would be really nice if I didn’t have to. Can Asterisk do that?
Speaking of shop noise, is Asterisk able to automatically turn up
the volume of a speaker when it detects the associated microphone
is picking up a lot of noise? That would be a really nice touch.
One more thing: I’d love to be able to take something out in the
yard with me so we can still communicate when she’s inside and I
have to be outside. I’m thinking of something like one of those
microphones that are worn on the ear like public speakers often use,
except two-way, not just a microphone. Something that’s always on and
leaves my hands free so I can work. The microphones are easy enough
to find, but I haven’t been able to find anything that has a speaker
as well as a microphone. Something that has a wire running down to
a unit that clips on my belt would be fine with me. It must have
enough range that can I stray from the house, and of course needs
to tie into the rest of the system. I’d have to be able to turn
off the base unit when not in use, but I doubt that’ll be a problem.
Does anyone know where I might find such a thing? Does anyone even
have some keywords that I might Google?
Again, I’m really sorry about asking all these questions without
doing more research on my own. I’m hoping for mercy. I am a bit of a
hacker, but the whole telephony, sound card, microphone, speaker thing
is outside my expertise, and the time I have to spend on this project
is pretty limited. I have two friends who are familiar with Asterisk
who have volunteered to help get me up to speed with it, and help me
with some of the configuration stuff, so I’m hoping some of you folks
might be willing and able to help with some of the rest. Those of you
who have taken care of a handicapped spouse will understand that it
can take a lot of time and energy, so the less of both I can expend
on this project the better. I’m hoping once it’s done, it will save
me some time and energy in taking care of her, as well as help me help
her in an emergency.
Thank you all,