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multi-source or switching to radio headphones for gallery?

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Anonymous
May 29, 2005 9:50:39 PM

Archived from groups: rec.audio.pro (More info?)

Hi there,

I'm looking for answers for this problem and so far have found little.

In a _large_ open space like an aircraft hanger (and old gasometer
apparently) there will be a dozen installed video works on large
screens, each video work has a stereo soundtrack. The curators do not
want to partition the space and would ideally like people to walk
around with headphones on and have the audio switch, either
automagically or manually, from one display/item to the next as people
wandered around. I've checked out some radio and infrared headphone
systems and none of them seem to be multi channel transmit/receive.
Maybe bluetooth is the answer? Infrared and bluetooth might
automatically switch based on proximity to a place, but that's not the
biggest problem as the place is happy have the headphones connected to
a little box to switch manually. I was thinking they might use a
similar (wired) system for simultaneous translation in the UN and so
on, but can find little info. Does any body have any info or ideas on
how to achieve this? Or any pointers at all?

Many thanks...
Anonymous
May 30, 2005 12:54:27 AM

Archived from groups: rec.audio.pro (More info?)

Thanks Dale, I've tried that in testing, but it does not seem very
reliable so far. I'm also concerned with battery life issues and sound
quality of IR links... But I'll give it more consideration.

Cheers,
Paul
Anonymous
May 30, 2005 5:40:47 AM

Archived from groups: rec.audio.pro (More info?)

Speakers are not really an option because of the sound spill from one
exhibit to another - and neither are water features. And the audience
can walk around some exhibits. FM headphones with presets might be a
viable option, with quite a few low power transmitters... I think Sony
has some FM headphones with hand-held control boxes which would make
the switching from one exhibit to another easily controllable.
Related resources
Anonymous
May 30, 2005 5:46:16 AM

Archived from groups: rec.audio.pro (More info?)

bkdog wrote:

> Hi there,
>
> I'm looking for answers for this problem and so far have found little.
>
> In a _large_ open space like an aircraft hanger (and old gasometer
> apparently) there will be a dozen installed video works on large
> screens, each video work has a stereo soundtrack. The curators do not
> want to partition the space and would ideally like people to walk
> around with headphones on and have the audio switch, either
> automagically or manually, from one display/item to the next as people
> wandered around. I've checked out some radio and infrared headphone
> systems and none of them seem to be multi channel transmit/receive.
> Maybe bluetooth is the answer? Infrared and bluetooth might
> automatically switch based on proximity to a place, but that's not the
> biggest problem as the place is happy have the headphones connected to
> a little box to switch manually. I was thinking they might use a
> similar (wired) system for simultaneous translation in the UN and so
> on, but can find little info. Does any body have any info or ideas on
> how to achieve this? Or any pointers at all?
>
> Many thanks...

Use the infrared ones, and carefully mask the IR transmitters so that
they don't overlap. Different transmitter for each track of program
materiel. Standard system parts now, all you have to do is build some
custom masks for the transmitters.

--Dale
Anonymous
May 30, 2005 10:48:49 AM

Archived from groups: rec.audio.pro (More info?)

Yeah, good idea, I'll investigate the induction loop systems. There is
video on each exhibit and the sound is in sync with it... so the
ipod/player idea can't work. I'm sure systems like I want exist, it's
just frustrating trying to treack them down...

Many thanks,
Paul
Anonymous
May 30, 2005 11:08:53 AM

Archived from groups: rec.audio.pro (More info?)

bkdog wrote:

> Thanks Dale, I've tried that in testing, but it does not seem very
> reliable so far. I'm also concerned with battery life issues and sound
> quality of IR links... But I'll give it more consideration.
>
> Cheers,
> Paul

You have to be aware of other IR sources in the area, and also the
direction that receiver on the headphone is facing. ( typically frontally,
and inclined upward around 20-30 degrees. ) IR will reflect from
surfaces that you may not expect it from, like polished stone and
metal.
Another possibility is low powered FM transmitters, similar to the
ones used to couple your CD player to a car radio. Then you can use
fixed tuning FM radio headsets. There are systems made specifically
for museums, but I've never used them myself, except as a tourist.
Yet another method is to use arrays of speakers suspended overhead
pointed straight down at the audience area. You can mask the sound spill
by adding a lot of white noise to the ambiance with speakers playing
the ambiance soundtrack, and things like fans and fountains.

--Dale
Anonymous
May 30, 2005 1:30:35 PM

Archived from groups: rec.audio.pro (More info?)

In article <1117414239.176842.47340@g47g2000cwa.googlegroups.com> pauld@koncon.nl writes:

> In a _large_ open space like an aircraft hanger (and old gasometer
> apparently) there will be a dozen installed video works on large
> screens, each video work has a stereo soundtrack. The curators do not
> want to partition the space and would ideally like people to walk
> around with headphones on and have the audio switch, either
> automagically or manually, from one display/item to the next as people
> wandered around.

I've been in museums where they have systems like this. I would think
that a good way to do it today would be to use a portable player such
as an iPod and let pepole select the program as they walk up to an
exhibit.

I'm not sure how to deal with theft - hand someone an iPod when they
walk in and expect them to return it when they leave - but perhaps
people who visit such exhibits are just honest, or maybe there could
be a deposit involved (admittedly a problem for kids who visit without
parents).

At the NAB show, they had "PDA Loading Stations" where you could point
your PDA's infra red window at the station and it would upload an
up-to-date schedule. Perhaps you could set up something like this for
those who brought their own loadable players, or rent players to those
who didn't have one.

An alternative to the infra red system is the magnetic induction loops
that they use for hearing assistance. The radiation of such a loop can
be fairly well controlled so that you get the station's program when
you get close enough to it.
'

--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
Anonymous
May 30, 2005 1:30:36 PM

Archived from groups: rec.audio.pro (More info?)

pauld writes:
> In a _large_ open space like an aircraft hanger (and old gasometer
> apparently) there will be a dozen installed video works on large
> screens, each video work has a stereo soundtrack. The curators do not
> want to partition the space and would ideally like people to walk
> around with headphones on and have the audio switch, either
> automagically or manually, from one display/item to the next as people
> wandered around.

The infra-red products would seem ideal. You can make the
emitters ("transmitters") directional so that you can only see/
hear them when you are in front of the corresponding screen.
And they are useless for other purposes, so risk of theft is
reduced (at least among visitors with half a brain. :-)
Anonymous
May 30, 2005 6:14:02 PM

Archived from groups: rec.audio.pro (More info?)

bkdog <pauld@koncon.nl> wrote:
>
>In a _large_ open space like an aircraft hanger (and old gasometer
>apparently) there will be a dozen installed video works on large
>screens, each video work has a stereo soundtrack. The curators do not
>want to partition the space and would ideally like people to walk
>around with headphones on and have the audio switch, either
>automagically or manually, from one display/item to the next as people
>wandered around. I've checked out some radio and infrared headphone
>systems and none of them seem to be multi channel transmit/receive.
>Maybe bluetooth is the answer? Infrared and bluetooth might
>automatically switch based on proximity to a place, but that's not the
>biggest problem as the place is happy have the headphones connected to
>a little box to switch manually. I was thinking they might use a
>similar (wired) system for simultaneous translation in the UN and so
>on, but can find little info. Does any body have any info or ideas on
>how to achieve this? Or any pointers at all?

Infrared does this already. When you are standing in front of a
transmitter, you can hear it. When you are not in line of sight of
a transmitter, you do not. The signal is all line of sight and you
can turn down the intensity on the transmitter to restrict even
that range.

The traditional way of doing this, though, is with an induction loop.
Look at the museum supply companies; there are a number of these
systems sold.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
May 30, 2005 11:41:07 PM

Archived from groups: rec.audio.pro (More info?)

>
> I was at a hamfest Sunday......

Mike...
were you at THE hamfest in Dayton?

Mark
WB2WHC
Anonymous
May 31, 2005 1:17:23 AM

Archived from groups: rec.audio.pro (More info?)

In article <1117460929.806508.30790@f14g2000cwb.googlegroups.com> pauld@koncon.nl writes:

> I'm sure systems like I want exist, it's
> just frustrating trying to treack them down...

They exist, but not likely as an off-the-shelf product, and it won't
be inexpensive. One approach is to have multiple FM transmitters (or a
multi-channel low power transmitter in a box) in the facility and
provide each visitor with a receiver. By tuning to each exhibit's
carrier frequency. With fixed-tuned receivers, you could have a
"channel" for each display. There are lots of
cheap-enough-to-get-stolen portable FM receivers on the market that
have programmable channels. Transmiters are more expensive.

I was at a hamfest Sunday where someone was selling a few 4-channel FM
transmitters in a single space rack. They worked in the commercial FM
broadcast band and they were only $50, but they were mono, not stereo.
I would have bought one to "broadcast" in my house and out to cars
parked in the driveway, but I passed. These were really beautifully
built units, probably costing upwards of $5,000 when new,



--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
Anonymous
May 31, 2005 1:22:51 PM

Archived from groups: rec.audio.pro (More info?)

In article <1117507267.825700.256940@z14g2000cwz.googlegroups.com> makolber@yahoo.com writes:

> Mike...
> were you at THE hamfest in Dayton?

No. I don't go that far. This one was in West Friendship, MD

Others nearby are:

Manassas VA - Sunday June 4
Frederick MD - Sunday June 19
West Friendship MD - Sunday July 24 (This one used to be at Timonium MD)
Gaithersburg MD - Saturday/Sunday September 10-11




--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
Anonymous
June 3, 2005 1:48:15 PM

Archived from groups: rec.audio.pro (More info?)

Yeah, but the induction loop systems have a very limited frequency
ressponse, and a bunch of other problems - I've done work in museums
before. Sennheiser makes some in ear monitoring kit that looks like it
will work, with user switchable receiving channels, and I'm not giving
up on infrared yet either, if I can make it work rpoperly in the space.
-paul
June 3, 2005 3:16:16 PM

Archived from groups: rec.audio.pro (More info?)

bkdog wrote:
> Yeah, but the induction loop systems have a very limited frequency
> ressponse, and a bunch of other problems - I've done work in museums
> before. Sennheiser makes some in ear monitoring kit that looks like it
> will work, with user switchable receiving channels, and I'm not giving
> up on infrared yet either, if I can make it work rpoperly in the space.
> -paul

Do the induction loops or infrared systems do stereo?

If so, how does it work? (I mean how does it accomplish that?

Mark
Anonymous
June 3, 2005 4:20:26 PM

Archived from groups: rec.audio.pro (More info?)

"Mark" wrote ...
> Do the induction loops or infrared systems do stereo?
>
> If so, how does it work? (I mean how does it accomplish that?

The baseband induction systems don't do stereo that I've ever heard of.
They work by just having 1 or more turns of wire around the covered
area and connecting directly to an amplifier. The "receivers" are just
electromagnetic coils connected to headphone amplifiers. They also
dont' seem very practical where you need separate coverage areas
adjacent to each other (as in the OP's museum application).

OTOH, IR has the advantage of higher bandwidth capacity and can
use separate "carrier" frequencies for the left and right signals. Kinda
a low-frequency version of having a dozen stations available on your
radio dial.
Anonymous
June 3, 2005 6:49:27 PM

Archived from groups: rec.audio.pro (More info?)

In article <1117822576.201461.121060@g49g2000cwa.googlegroups.com>,
Mark <makolber@yahoo.com> wrote:
>
>
>bkdog wrote:
>> Yeah, but the induction loop systems have a very limited frequency
>> ressponse, and a bunch of other problems - I've done work in museums
>> before. Sennheiser makes some in ear monitoring kit that looks like it
>> will work, with user switchable receiving channels, and I'm not giving
>> up on infrared yet either, if I can make it work rpoperly in the space.
>> -paul
>
>Do the induction loops or infrared systems do stereo?
>
>If so, how does it work? (I mean how does it accomplish that?

The infrared systems do. Basically the infrared transmitter puts out
a high frequency carrier modulated onto the infrared beam... the
LED array flickers at some carrier frequency in the MHz region... the
receiver picks that up and demodulates it.

This eliminates noise from things like flickering fluorescent lights.
It also allows you to put multiple carriers for stereo on a single
IR panel.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
!