Film-Tech Forum ARCHIVE: What is a "loop system" (hearing impaired)?

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Posted by Mike Blakesley (Member # 26) on 12-23-2010, 08:55 PM:

I had a customer tonight ask me if we had a hearing-impaired system, so I gave him the typical headseat/walkman-type device that we have. He asked if we had a "loop system" and I said we only have this type of system. He said, "After the show I'll talk to you about a loop system, it's way better than this type."

So my question is, what IS a "loop system?" I never heard the term before. Is it really "way better?" Should I be saving up for it?

Posted by Kenneth Wuepper (Member # 1174) on 12-23-2010, 09:14 PM:

Mike,

The "loop system" to which your customer refers is a common, non-radio magnetic broadcasting system.

The room is surrounded with wire loops that are fed by an amplifier. This creates a magnetic field with the sound as variations in the magnetic field.

The customer, with a properly equipped hearing aid, can switch to a little coil in the device that picks up the magnetic field from a telephone earpiece. The device is sensitive to magnetic fields and can pick up and amplify the sound your loop is transmitting.

These systems are very good and relatively inexpensive for the theatre to implement. The drawback is that it requires the customer to have and to use the telephone feature of the hearing aid. Customers without the hearing aid device cannot get the cinema sound from the loop transmitter.

Posted by David E. Nedrow (Member # 4981) on 12-23-2010, 11:45 PM:

Mike,

When we did our renovations, I installed the induction loop wire around the auditorium before the wall treatments were installed. Of course, I don't have the money yet for the rest of it yet. [Wink]

The nice thing about an induction loop system is that any hearing aid, or cochlear implant, with a telecoil will be able to receive the audio. They also have induction loop headsets for people without properly equipped hearing aids. That way, you don't have to maintain two systems, once the loop is installed.

They have some information (not technical) at HearingLoop.org.

Look at Vivid Acoustics and Harris Communications for actual systems. You're generally looking at around $1000 for the whole thing, including induction wire.

Here's a good overview at Marc's Technical Pages.

Oh, the drawback to induction loops -- though it doesn't affect single-screeners like us -- is that the sound can "leak" to adjacent auditoriums, assuming those adjacent spaces are also looped. Note also that a hearing aid customer in an adjacent, non-looped room may tune in the looped auditorium audio thinking they are getting the soundtrack for the theatre they are in.

-David

Posted by Harold Hallikainen (Member # 5405) on 12-24-2010, 12:26 AM:

Many hearing impaired headphones have magnetic field leakage, just as hearing aid compatible telephone receivers, for which the t-coil hearing aids were designed. We recently tested the USL IRH-230 headphones with a person with a t-coil hearing aid. She said it sounded great.

Harold

Posted by Mike Blakesley (Member # 26) on 12-24-2010, 01:05 AM:

Thanks for the great info, guys. The customer never said anything after the show -- maybe our existing system worked well enough for him or he just forgot about it. But, it's something worth looking into when our current system gives out.

Posted by Louis Bornwasser (Member # 3063) on 12-24-2010, 06:22 AM:

Works great in the UK. (Should have had it in the US.) Louis

Posted by Steve Guttag (Member # 268) on 12-24-2010, 06:52 AM:

We have often supplied Williams Sound NKL 001 neck loops. They will turn any device with a 3.5mm audio output (that can drive an 8-16 Ohm speaker/headphone) into a T-coil loop.

So that can be the other way to skin the cat...as it were. Adapt an existing IR system for loop for those customers that desire it and have the suitable apparatus.

-Steve

Posted by Mark Hajducki (Member # 1732) on 12-24-2010, 07:58 AM:

Induction loops (for cinema usage) have often been replaced with IR based systems. With the desire/requirement to provide audio description, as well as amplified audio, a multiple channel system is required.

If budget allows having both systems in use would be good as customers will not have to borrow equipment (with the risk of it not being returned).

quote: Kenneth Wuepper
The drawback is that it requires the customer to have and to use the telephone feature of the hearing aid. Customers without the hearing aid device cannot get the cinema sound from the loop transmitter.

You can get induction loop receivers that work in the same way as receivers for the IR systems.

quote: Steve Guttag
We have often supplied Williams Sound NKL 001 neck loops. They will turn any device with a 3.5mm audio output (that can drive an 8-16 Ohm speaker/headphone) into a T-coil loop.

Having one of these may be the best option as it would allow people to use their own hearing aid (which would be better than external headphones) reducing the distraction to other customers.

quote: David E. Nedrow
Oh, the drawback to induction loops -- though it doesn't affect single-screeners like us -- is that the sound can "leak" to adjacent auditoriums, assuming those adjacent spaces are also looped. Note also that a hearing aid customer in an adjacent, non-looped room may tune in the looped auditorium audio thinking they are getting the soundtrack for the theatre they are in.

A local (now closed) 5 screen cinema had plans at the entrance to each screen showing where to sit to get best reception for the induction loop. They may have planned the loops so as to reduce leakage between screens.

Posted by David E. Nedrow (Member # 4981) on 12-24-2010, 11:31 AM:

quote: Mark H.
A local (now closed) 5 screen cinema had plans at the entrance to each screen showing where to sit to get best reception for the induction loop. They may have planned the loops so as to reduce leakage between screens.

They may have been planning on just laying the loop around a small set of centrally located seats. That way, they could direct people to sit in that area, but the coils would be far enough from each other that the leakage wouldn't happen.

I would think that if I were hard of hearing, I'd rather use the loop system, strictly from a hygiene perspective.

Another drawback to coil, in a theatrical sense, is that it's mono only.

We have IR emitters here, but the previous people destroyed most of the needed equipment to drive and use it. They had a roof leak that went unfixed for some time, and, in addition to rotting the masking fabric, it leaked on the transformer/amplifier and ruined it. They also left batteries in all of the headsets, which leaked all over the interior boards in them.

Posted by David Favel (Member # 1125) on 12-28-2010, 06:36 PM:

Having 2 cinemas side by side, we installed our loop 1 meter from the walls. No bleed between cinemas and seems to cover all seats. There are however sweet spots that if someone is hearing a bit of fuzz, suggest they move over a cuople of seats.
Loops are a legal requirement in NZ.