Cohousing-L Mailing List: more on soundfield systems

[Laura Polich (laura.polich]

I would just like to clarify that the Soundfield amplification systems in
use in classrooms and other group settings is not the same as the old
Public Address (PA) systems. There are kids in classrooms with severe and
profound hearing loss using hearing aids and cochlear implants, and they do
fine with soundfield systems. Soundfield systems improve the
signal-to-noise ratio, not just make the signal louder.  I think the
problem you pointed to is a hearing aid issue, not a soundfield
amplification issue. At Daybreak we have members who use hearing aids and
cochlear implants and no one has ever complained  that it is too loud. I,
myself, have complained about some settings being too loud, but that is
because those settings result in feedback (high-pitched squeal that is
definitely unpleasant) when the microphone gets too close to the speaker.
Adjusting those settings makes the squeal all go away. Also, we do not
limit our soundfield's use to lectures or presenter before an audience. We
use it for every plenary. It comes with two microphones. The facilitator
uses the main one, and the other one, the pass-around microphone, is used
by any one wanting to comment or make an announcement or ask a question. It
means you have to have a "runner" to get the microphone to the next person
who wants to speak, but that is not difficult to organize. The soundfield
system also has a way to be plugged into a television or a computer so a
movie or video presentation can be heard easily by everyone.

Another thing about hearing aids: today's hearing aids are ALL digital
(i.e. two little computers sitting behind your ears). No one fits analogue
hearing aids any more. That means there is a lot of signal processing
available, but the hearing aids have to be programmed to use those signal
processing algorithms. All hearing aids nowadays have multiple "limiters"
so that a ceiling can be set at which the hearing aid stops increasing the
amplification (usually an individual tolerance, so the aids have to be fit
taking the individual's needs into account -- you can't use a
"one-setting-for-everyone" process.) Also, another sound processing
algorithm called "compression" will improve speech understanding by using
various compression strategies to keep the speech in a comfortable range
for the individual. There are bunch more signal processing algorithms
available in modern hearing aids, but the person programming the aids has
to know their stuff and also has to be told what problems the listener is
having. When I was fitting hearing aids, I always told my clients: "if you
aren't happy with your aids, please come back, explain what you don't like,
and let me try to improve the programming of your aids".

I also want to add to this topic and point out a difference in soundfield
systems that many in cohousing are probably not aware. There are infrared
soundfield systems where the signal is sent over light waves out into the
listening area. I have seen them mostly in movie theaters or performance
venues where the overhead lights are turned off during a performance and
where there are no windows.. The problem with these are that the listener
has to wear a device (go to a service desk, request a device, leave ID to
keep you from running off with that device, and then return it at the end
of the performance to get your ID back), and no hearing aids/CIs have a way
to use the light signal. A listener has to use the provided receiver  They
only work if the receiver device has direct line-of-sight access to the
signal. If you are sitting next to a barrier (a column that blocks the
light from the transmitter) you'll have to move or cannot use the device.
They also do not work well in daylight because the daylight interferes with
the light being sent by the transmitter. So, just a caveat to communities
thinking about this: please do not get infrared systems.

A problem with loop systems is that they are usually hardwired into a room
(the proper cable has to be put into the walls or floor or ceiling) so the
cost is upfront, best to do when building or doing major renovations.
Soundfield systems can be added anytime without any need to open walls, and
they very portable so they can be set up in different rooms for different
purposes and moved around easily. Ours has a carrying case so it is easy to
transport the system from place to place. I believe there have been
industry  attempts to come up with a portable loop, but since few people
have telecoils, manufacturers are probable loathe to put in much R&D money
into that project. The biggest selling point to me when I was researching
Daybreak's option is that with a loop only people with hearing aids or
people willing to put on a neckloop benefit from the loop. Soundfield
systems benefit every listener in the room: those with normal hearing,
those with normal hearing but difficulty hearing in background noise, and
those with hearing aids/CIs. The strain of listening is reduced for
everyone -- less fatigue, less annoyance at people who don't talk loud
enough, less annoyance at people who simply must hold a conversation with
their neighbor during a meeting.

Laura
Audiologist on the verge of retiring