Induction Loop Technology: Gotcha!

induction loop

First, I want to share some great feedback from one of our readers, David-Lloyd Klepper, about my recent series discussing industry professionals who sell services they cannot provide, specifically, “Piece Of The Pie” (October 2016). David’s feedback: “Excellent column, 100% right,” followed up later with these words of wisdom: “I think an analogy would be that, when you are a sub, take the job only with the understanding that you have direct communication with the client, with the prime contractor always receiving copies and having a presence at conferences.” Thank you, David, for taking the time to share. I could not have said it better!

Before I move into this month’s discussion, which relates to manufacturer training, I want to state that it’s important for those providing training to incorporate great content. One of the ways I judge the content of such training is if I can say “Wow, I always wanted to know that” at the end. It’s not enough to just train with sometimes specialized and, perhaps, benign content; if every one of your attendees can’t say that, you are on the wrong track…in my opinion, of course!

A few months ago, I took a course provided by Williams Sound related to induction loop assistive listening systems. The two-day program concluded with a test and certification, and 12 RU InfoComm credits to boot. When I left the class, I said, “Wow, I always wanted to know that….” The class was so relevant that I want to share a few things about this aspect of assistive listening technology.

The class was taught by Mike Griffitt, US Technical Training Manager, in conjunction with Tony W. Strong, National Sales Manager. I was impressed with the class, supporting documentation and the overall message, as well as the presenters’ astute professionalism and knowledge. I highly recommend this class if you plan to work with induction loop technology for an assistive listening system.

A note here, whether you are a consultant or integrator: Our population is getting older, and this is an emerging opportunity in our industry. According to the World Health Organization, about 40 million folks in the US are considered “hard of hearing,” which is about 17% of the population. That percentage increases dramatically after the age of 65.

If you are not selling this service, I ask, “Why not?” Induction loop technology is likely to become more prevalent as time goes on, and more than just basic AV skills are required for a successful and profitable experience for all. This is a way to increase your visibility in the AV market and distinguish yourself from others, as well, because these systems are profitable.

The catch is that this technology has quite a few variables that must be qualified in advance, such as a site survey with a field strength meter (and knowing what to do with it). In other words, there can be lots of “gotchas,” so training is essential.

This class brought back fond memories of college physics classes (which I enjoyed immensely; at one point, I was considering becoming a physicist). It involved magnetic fields infused with audio, distributed by running a current through copper wire in a contained area, and not only being able to predict the field strength, but measure and commission it, too!

Individuals whose hearing aids can be switched to telecoil, or t-coil, or who have a cochlear implant, will experience the equivalent of wearing an FM headset and receiver when they step into a space equipped with induction loop technology.

Rather than make a list of these “gotchas,” Tony shared a situation he recently went through on a large, new commercial construction project of 15 rooms with a ceiling height of 17 feet. The AV is consultant-driven and goes out for bid. Issues 1 and 2: The consultant messed up here twice, first with the design and then with the specifications. For the design issue, the consultant specified that the “loop” be placed above the finished ceiling, which is dead wrong with such high ceilings. Imagine the “field” that is picked up by the listener’s hearing aid, which is about five feet off the floor.

This loop’s signal radiates vertically up and down, and is adjusted to put out the appropriate level at five feet above the floor. That means that the distance from the loop to the listener for this room is about 12 feet away (down), and extends above the floor to the room above. In this case, many rooms were above each other on different floors, so this is a “disaster” design!

In addition, the consultant did not specify that the bidder on this system must have experience in similar size and scope for this project. This is no different than providing assurance that a trunk slammer is not bidding on the project, and requires some industry certifications, such as CTS-D, CTS-I, DMC-E, XTP-E, etc.

The winning bidder was an electrical contractor (EC) who had no experience with induction loop technology. The EC felt that it was just low-voltage and he could handle it! As luck would have it, the EC did not follow the consultant design and used a “foil tape under the carpet approach” that did avoid the above-ceiling issue previously described (only because it would have cost more for lift rental and labor to install in the ceiling…pure luck).

Tony found out about the project after the foil tape was laid down (in an unknown pattern) from the EC, who was looking to purchase the induction loop driver equipment. Lucky for everyone, and credit to Williams Sound for not just making another sale and sending the equipment out the door. They asked the EC a series of qualifying questions to determine, among other things, what equipment the installation would require. After finding out that the many variables of designing and installing an induction loop system were never accounted for (and convincing the client that it would behoove them to have professionals help), the EC hired Williams Sound to assist in commissioning the system with its Tech Blue Team.

Kudos to Williams Sound for offering this service. We don’t see many manufacturers, if they were not involved from the beginning, offering such assistance on the back end of a project.

Their first step when onsite was to verify continuity of the installed foil tape “loops” already located on the floor under the carpet in 15 rooms. Disaster: Not one room passed a continuity test. As a result, all the carpeting had to be removed so this could be fixed (one room had 10 locations where the tape was severed by the carpet installers!).

You can imagine the face on the general contractor, EC, consultant and client when thinking not only of the cost, but the delay in the timeline. “Gotcha”: Carpet installers must be made aware up front that the foil tape they are about to cover is not decorative and that it cannot be cut, moved or damaged in any way.

The next step is the standard metal loss test looking at 100Hz, 1KHz and 5KHz. This is necessary to determine how close the loop segments must be to meet the Induction Loop Standard, IEC 60118-4, which allows for no more than ±3dB from a 0dB reference point. The findings revealed a large drop at 5KHz, meaning the floor was likely concrete over steel pan decking, which causes high-frequency loss. This is another “gotcha.” The layout of the loops can compensate for it. In this case, the simple array pattern installed was inadequate, which became visible with the carpet removed.

All 15 rooms had to be designed properly (length and pattern of the foil tape) using calculations to determine loop size and pattern (provided by Williams Sound), and then redone to meet the IEC specifications. Then, finally, they recommended the necessary hardware. Ouch: more money for new foil tape and labor, more delays. In the end, when all was said and done, the client and users of the new system expressed their gratitude for making things right, as well as how well the induction loop technology system worked.

There you have it. I have not been able to detail every “gotcha” here, along with all the technical details (I will likely follow up with more about this subject another time), but the moral of the story is, “Do it right the first time and, of course, induction loop technology is not something you can just ‘brute force,’” You need specialized test equipment and knowledge. I recommend taking a training course about this technology, whether this class from Williams Sound or one from another manufacturer.

Please note: I met a member of the Tech Blue Team in the Bose Consultants’ Lounge at InfoComm a few years ago. I was impressed with their effort and have been on the company’s newsletter list since then. As a result, I received an invite for the training course, which has spurred my interest in the subject.

Just to be clear: Other induction loop technology systems are available. We take our role as an independent publication seriously and do not review equipment or endorse any specific manufacturers. However, when I have a positive (or negative!) experience that can help my readers, I will share that with you.

On another note, we have added a MANUFACTURERS section to Doug’s Docs under Resources at Sound & Communications’ website. As I find pertinent documentation that a manufacturer is willing to share, it will be posted. In this case, in conjunction with Williams Sound, we have come up with an Induction Loop Technology Questionnaire that you can download. This will help you to determine on the head end if induction loop technology is the right approach for your client. It includes a matching answer key that will help you make that determination, along with other documentation.

I ask that manufacturers and readers willing to share questionnaires, checklists and other documents that we can post to Doug’s Docs contact me. We want this to be a place to “share” and make our industry better. Send comments, examples and stories about your experiences to

Tony W. Strong

Tony W. Strong, Williams Sound’s National Sales Manager, has worked in pro audio for many years as an integrator, sound engineer and sales management professional. Tony says, “Don’t fall into the ‘trap’ that this is just another technology. Do it right the first time and get the training!”

He can be reached at:

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