Designing for People with Hearing Loss  

Imagine going to the theater but being unable to hear the dialogue clearly and missing the punchlines over and over, despite constantly adjusting the volume on your hearing aid. Imagine trying to fill a prescription and struggling to communicate with the pharmacist about the dosage and timing. Imagine standing on a subway platform and not being able to hear the announcements over the group of rowdy teens a few feet away. This is the daily experience for millions of Americans who have hearing loss, and designers can do something about it.

All images courtesy of Contacta

Designers can improve the everyday experience of people with hearing loss by equipping public, assembly, and commercial spaces with a hearing loop.

It is estimated that one out of seven Americans has some degree of hearing loss. According to the World Health Organization (WHO), an estimated 22.1 percent (57.1 million individuals) in the United States over the age of 12 have experienced hearing loss in at least one ear, and 13.8 percent of the population (35.5 million) have lost hearing in both ears. The number of people with binaural hearing loss (in both ears) is expected to grow to more than 41 million by 2025.

While many people with hearing loss have hearing aids, the technology still struggles to find the signal of interest in a loud room, often drowning the wearer in ambient noise and causing incredible frustration. Designers can improve the experience of people with hearing loss in the built environment by specifying an assistive listening technology that inconspicuously delivers the lecture, presentation, or dialogue directly to the person’s hearing aid, minimizing the ambient noise that can be so distracting. This assistive listening system enables people with hearing aids to clearly hear the featured performance and more easily participate in regular day-to-day activities, such as making a deposit at the bank or purchasing a ticket at a bus station.

This course will take a deeper dive into the different systems available to designers to improve hearing accessibility in both large venues and one-on-one encounters and provide insight into the dramatically different user experience that each solution offers individuals with hearing loss. To better understand the various assistive listening devices available and the strengths and weaknesses of each, it makes sense to start with a quick overview on the mechanics of hearing loss, a few of the terms used to discuss this issue, and an explanation of why hearing aids just aren’t enough.

Defining Sound and Hearing Loss

Sound waves are often described with two metrics: decibels (dB), which measure the intensity of the sound, and hertz (Hz), which refer to the frequency of the sound wave. The human ear can hear a wide range of frequencies broadcast at a number of intensities. More specifically, sounds can be detected by the human ear from the very low 20 Hz to the very high 20,000 Hz. Low-frequency sounds include the beat of a bass drum, the blast from a tuba, and the grumble of thunder, while high-frequency sounds are found in whistles, chirping birds, and the squeals of a child.

As it relates to the level of sound, a person’s hearing threshold describes the level of sound that can be detected by that person’s ear. The hearing threshold of a normal, healthy ear is 0 dB across the full range of 20–20,000 Hz. A soft whisper is often measured at 30 dB, while an ordinary conversation is carried on at around 60 dB and a loud radio produces sound at about 80 dB.

When a person has hearing loss, he or she may have a higher hearing threshold, meaning that sound levels must be louder to be detected by that person’s ear. Mild hearing loss is categorized as a condition where the quietest sounds a person can hear is between 25 and 40 dB. For people with moderate hearing loss, the hearing threshold is even higher, between 40 and 70 dB. People with moderate hearing loss can have difficulty keeping up with conversations if not using some type of hearing aid.

People with hearing aids and cochlear implants often struggle to hear announcements or other important audio signals in areas with a lot of background noise.

A Closer Look at How Hearing Aids Work

Hearing aids are designed to help a person hear by making sounds louder. The basic design for a hearing aid consists of a microphone, amplifier, battery, and speaker. The microphone picks up the sounds from the person’s immediate environment, the amplifier converts the sound wave into electrical signals that are adjusted based upon the unique needs and preferences of the wearer, and then the amplified and altered signals are converted back into sound waves and delivered to the ear through the speaker.

Unfortunately, one of the shortcomings of hearing aids that regularly frustrates the people who use them is their struggle to filter out extraneous noise. Hearing aids lack the ear’s natural ability to identify the signals that a person wants to focus on and dismiss background noise. A hearing aid amplifies all the noise it detects in the surrounding area, both the important signals and the ambient ones, and that creates a lot of different noises for a person with hearing loss to wade through. As a result, a person wearing a hearing aid will still miss key parts of a lecture, directions, or other important information because the hearing aid detects and amplifies those signals as well as the conversation occurring a few feet away, the footfalls on the concrete, the rustling bag of chips, and the whirring of the HVAC unit.

Background noise and distance from the speaker often create barriers to comprehension for people with hearing loss, even if they are wearing a hearing aid or have a cochlear implant. Even with making all the noises louder, people with hearing loss can still have significant problems understanding speech, exert high levels of effort to comprehend and decipher what they are hearing, and experience poor or unnatural sound quality. “The ability to understand speech in the presence of noise is often degraded in people with hearing loss,” explains Andrew King, auditory neuroscientist at the University of Oxford in England. “It’s the single biggest challenge of someone with a cochlear implant.”¹

In order to help people with hearing loss more easily comprehend and participate in what is going on around them, they need to increase the signal-to-noise ratio (SNR) in their environment. SNR compares the level of signal strength to the level of background noise. It is generally expressed in dB. Higher SNR values indicate that the audio signal is louder than the surrounding noise, meaning the signal will be clearer and easier to understand.

In the article “Hearing Loops: The Preferred Assistive Listening Technology” published in the Journal of the Audio Engineering Society in April 2015, the authors wrote, “Research has indicated that hard-of-hearing listeners may require an increase in signal-to-noise ratio of more than 10 dB, some as high as 25 dB, to achieve the same word recognition as a normal-hearing person in the same situation. A decline in the signal-to-noise ratio makes it more difficult for people with hearing loss to effectively discern speech from what would be considered a mild background noise to listeners with hearing within the normal range. The result is that users of even the most advanced digital hearing instruments or cochlear implant processors frequently report that they are able to hear but not fully comprehend spoken information.”

Introducing Assistive Listening Systems

Assistive listening systems are designed to turn up the strength of the signal of interest, improving the SNR and making it easier for a person with hearing loss to accurately decipher what is being said.

These systems typically feature three components: a microphone, a transmitter, and a receiver. The microphone picks up the signal (the speech, music, or combination of the two) and sends it to a transmitter, where it is converted into an electronic signal and sent to the receiver, which is attached to the person with hearing loss.

While there are a growing number of assistive listening systems, the three most common types are a frequency modulation/radio frequency (FM/RF) system, an infrared (IR) system, and an audio frequency induction loop, also referred to as a hearing loop. Each of these systems differs in the way they transmit the signal to the receiver and the type of receiver they require, which impacts the level of convenience and the quality of the sound signal they provide.

Audio Frequency Induction Loop/Hearing Loop

Hearing loops are an assistive listening solution that are unique in their ability to send the enhanced audio signal directly to a person’s hearing aid or cochlear implant, without requiring the person with hearing loss to wear a separate receiver, headphones, or a neckloop. The key difference is that these systems utilize the telecoil technology that already exists inside a hearing aid or cochlear implant as the receiver.

Hearing loops send the audio signal directly to a person’s hearing aid, allowing attendees with hearing loss to hear a speaker more clearly without wearing additional equipment.

Here’s how a hearing loop works. A copper wire is installed throughout an assembly area, in either the floor or the ceiling. A hearing loop driver, the system’s amplifier, connects to the microphone or sound system at the site and the cooper wire. A current is driven through the copper wire, creating an electromagnetic field within the audience. When the speaker talks into the microphone, the audio signal is transmitted over the electromagnetic field and received by the telecoil in the hearing aid or cochlear implant of the person with hearing loss. The person receives the signal he or she is interested in, without all of the background noise competing with it. The improved SNR allows the listener to hear and understand the words being spoken with greater clarity and ease.

Today, it is estimated that virtually all behind-the-ear hearing aids and cochlear implants, along with most in-the-ear devices, are equipped with this telecoil technology. This means that most people with hearing loss who use a hearing device are equipped to receive the clearer signal transmitted by the hearing loop system. In order for a hearing aid or cochlear implant with a telecoil to detect the signal sent over the electromagnetic field, the telecoil must be activated. The wearer activates the telecoil by turning the t-switch in the hearing aid on, which is often done with the push of a button. When the t-switch is on, the microphone in the hearing aid that picks up the local environmental sounds is deactivated, and the person with hearing loss only hears the sounds being transmitted by the hearing loop. This dramatically improves the SNR of the speech, presentation, or play that the person is attending.

Those with hearing loss who do not have a hearing aid with a telecoil can also benefit from the clarity offered by the hearing loop. A venue with a hearing loop will often offer portable hearing loop receivers that come with earbuds or headphones. A person simply wears the receiver and the available earbuds or headphones to receive the enhanced audio signal being sent over the assistive listening system.

FM/RF System

FM/RF systems transmit the sound signal to the receiving device wirelessly through radio waves. While there are FM accessories that can be purchased for hearing aids that would allow an FM/RF system to transmit the wireless signal directly to a person’s hearing aid, these are quite costly and have not been widely adopted. This means that, for most people, if a venue offers an FM/RF assistive listening system, the people with hearing loss will need to find and wear additional pieces of equipment to be able to access the signal. Those additional components include a receiver and the headphones or ear buds that accompany it.

A neckloop is a necklace-sized loop of wire that is plugged into the FM/RF receiver. The neckloop converts the sound signal from the FM/RF receiver into electromagnetic waves and radiates them so that they can be received by the activated telecoil in the person’s hearing aid.

IR System

IR systems transmit the sound signal through a transmitter and receiver with infrared light, the same IR technology that is often found in television remotes. Just like the FM/RF system, an IR assistive listening system also requires a direct line of sight between the transmitter and receiver. The person with hearing loss wears a receiver and headphones to hear the presentation with greater clarity and without the distraction of the background noise.

These systems often include multiple IR transmitters (also called IR radiators) to provide the necessary line-of-sight coverage throughout the assembly area. However, it can still be difficult to achieve an unobstructed connection around the perimeter of the room.

Performance Comparison of FM/RF, IR, and Hearing Loops

There is a dramatic difference between the experiences that these three assistive listening systems offer to someone with hearing loss. In order to select the right solution for a project, its important to consider the unique performance characteristics of each type of system in terms of usability, sound quality, user preference, potential interference, ease of maintenance, universality, and the ability to be used in transient applications.

Hearing loops, FM/RF, and IR assistive listening systems offer a dramatically different experience to people with hearing loss attending a performance or lecture.

Usability

The usability of the various assistive listening systems is very different, especially when considered in terms of the experience that a person has using the systems and the number of users that each system can support.

Hearing loop systems send the audio signal directly to a person’s hearing aid or cochlear implant, enabling those people with hearing loss to enter a facility and begin accessing the signals sent over the assistive listening system by simply activating the telecoil mode in their hearing aid or cochlear implant with the press of a button. Both FM/RF and IR assistive listening systems require users to borrow receiving devices and headsets from the venue. This has a few notable setbacks, as it is not very convenient, and it takes time both before and after the engagement. When a venue has an FM/RF or an IR assistive listening system, attendees with hearing loss will need to find the desk where the equipment is available, be trained on how to use the various pieces, and check everything in and out. Another common issue is that many users are reluctant to borrow equipment due to hygiene concerns over shared headphones and ear buds.

There is also a difference in the number of people who can use a hearing loop and the number of people who can use an FM/RF or IR assistive listening system at the same time. When a hearing loop is installed into a space, anyone sitting in the area can turn on their telecoil and receive the audio signal. There is an unlimited number of simultaneous users with a hearing loop. FM/RF systems and IR systems can only be used by a person wearing a receiver. The number of people who can benefit from the assistive listening technology is limited to the number of receivers and headsets that are kept on hand at the site.

Sound Quality

There is also a dramatic difference in the sound quality that is offered from one type of assistive listening system to another. When hearing aids are fitted onto a person with hearing loss, the user participates in a process that customizes the way the hearing aid modifies the original sound to compensate for the person’s specific degree and pattern of hearing loss. It is also adjusted to meet personal preferences so the wearer enjoys the sound he or she hears. Hearing loops capitalize upon the work that has already been done by the wearer and the hearing specialists by using the person’s existing, customized hearing device to deliver the audio signal to his or her ear. When FM/RF and IR assistive listening systems deliver the audio signals through headphones or ear buds, the wearer must often remove his or her custom-fit hearing devices for the one-size-fits-all headset. In the swap, the person with hearing loss loses the clarity and customization provided by the hearing aid and instead gets distorted sounds at a higher volume.

User Preference

The convenience of using the hearing loop system and the sound quality it provides may explain why this technology often receives better reviews when compared with the other assistive listening systems. In a recent study comparing the experience of listening to a speaker in a large venue with a hearing loop, an FM/IR system with a neckloop, and an FM/IR system with headphones, 86 percent of the hearing aid users preferred listening with the hearing loop and their own hearing aid device instead of the other assistive listening systems.

Another study by Kochkin et al. asked hearing loop users to compare their listening experience in a looped venue with and without the support of the hearing loop. They rated their experience on a scale from one to 10, where one meant that the user effectively heard nothing and 10 indicated that the user heard every word of the performance. When listening without the hearing loop, only 14 percent of respondents rated their experience at eight or higher. After activating the telecoil in their hearing aid and getting the message delivered directly to their device, 86 percent of the respondents rated their experience in the venue at eight or higher.

Signal Interference

For people with hearing loss, the key problem is that the SNR is not strong enough on its own, so the signal of interest is camouflaged and weakened by other ambient sounds. Assistive listening systems improve the signal strength of the speech or presentation by cutting out the background noise and delivering the sound directly to the person’s ear. However, each type of signal—the IR, the RF, and even the hearing loop—can experience interference that compromises its strength and clarity. Infrared signals, for example, can be compromised in sunlight or whenever the direct line of sight between the receiver and the transmitter is obstructed. Radio waves from other RF devices can interact with FM/RF signals and cause interference or disruption.

By specifying a hearing loop system into a venue, designers transform the experience of the people with hearing loss in attendance, allowing them to hear announcements and be more fully engaged in the event.

Electromagnetic interference (EMI) can interfere with the signal delivered in a hearing loop system. When EMI is present, the person with hearing loss often hears a buzzing sound, which detracts from the transmitted audio signal. EMI can be caused by defective HVAC equipment and water heaters, neutral-to-earth faults, or electrical wiring that is not compliant with the National Electric Code (NEC). Most new buildings are constructed to satisfy the NEC and/or include ground fault interrupters, which minimize the occurrence of EMI. EMI is more common in older buildings and can be resolved by an experienced electrician.

Universality

Universality is also an important consideration when designing a space that needs to be accessed and understood by people of all ages with different levels of impairment and using a variety of hearing devices. The hearing loop is compatible with any telecoil-equipped hearing device, regardless of the manufacturer of the hearing device. While attendees with hearing loss must seek out the location to borrow the FM/RF and IR systems, the telecoil mode can be activated in a hearing aid with the push of a button. The hearing loop offers adults and children, with varying degrees of mobility, the clearest, most fine-tuned audio signal that can be accessed with the fewest extra steps.

Ease of Maintenance

There are also different maintenance requirements for the FM/RF, IR, and hearing loop assistive listening systems. In venues that offer the FM/RF and IR systems, the receivers and headphones and ear buds must be organized and kept clean and functional. This includes ensuring that the batteries in the receivers remain fresh enough to sufficiently power the devices. In practical application, this is often challenging. It can be difficult for staff to locate the receiving devices and headsets. Once they are found, they are often dysfunctional.

Hearing loop systems are virtually maintenance free. There is no communally shared equipment that must be regularly disinfected. There are no batteries to change. The hearing loop systems are easier for users to use and staff to maintain. And, according to the 2010 ADA Standards, if an area is equipped with a hearing loop, it is not required to also offer these FM/RF or IR assistive listening systems.

Transient Applications

Although much of the conversation thus far has focused on the experience that the assistive listening system offers a person with hearing loss in a large assembly area, people with hearing loss also struggle when trying to communicate with a person one-on-one. Talking to a teller at the bank, purchasing tickets at the box office, renewing a driver’s license, checking in at an airport, and basically any scenario where a person with hearing loss must communicate amidst a high level of ambient noise can present difficulty and cause frustration.

People with hearing loss also struggle when trying to communicate in one-on-one situations, and hearing loop systems are the only assistive listening solution that can be used in these applications.

Hearing loops are the only assistive listening system that can be conveniently used in these transient one-on-one communication situations. While FM/RF and IR systems would require that the bank tellers or customer service representatives hand over ear buds and receivers to every customer with hearing loss in the line, people can use the hearing loop technology by simply activating the telecoil mode in their own hearing aid. Once activated, the hearing loop will cut out the background noise and enable the person with hearing loss to hear the teller or sales representative with greater clarity.

Beyond convenience, hearing loops offer hearing assistance with a greater degree of privacy. The person with hearing loss never needs to ask anyone for additional equipment. Spaces equipped with a hearing loop often post signs to inform people that hearing loop technology is available. A person with hearing loss will see the sign and simply activate his or her own telecoil mode. No additional action is required from the staff members; they simply conduct the transaction as usual.

This technology can be installed in any number of places, including pharmacies, airports, retail check-out counters, libraries, information booths, and any place where clear and convenient interactions are critical to conducting daily business.

Hearing Loop Systems for One-on-One Situations

With such broad potential application, it is important to spend a moment detailing the types of hearing loop systems that support these one-to-one communications. There are two types of one-to-one hearing loop solutions. One is designed for a typical counter application. The other, referred to as a speech transfer system (STS), is uniquely designed to improve communication where a glass pane, security screen, or other security barrier is present.

One-to-One Counter Loop Systems

Counter hearing loops are used to facilitate short-range, one-to-one communication. These systems consist of a microphone placed behind the counter to capture the voice of the teller, pharmacist, or employee, a small loop aerial that creates the electromagnetic field over which the audio signal will be transmitted, a hearing loop driver, and a sign that indicates the counter is fitted with a hearing loop. The system is designed to remain on continuously so a person with hearing loss never has to ask for assistance. Once the person steps inside the electromagnetic field created by the loop, he or she simply activates the telecoil in his or her hearing aid or cochlear implant to experience the clearer audio signals sent directly to his or her hearing device. The counter loop works within a defined area, allowing a hearing loop to provide a clearer signal and protect the confidentiality of the conversation. There is no risk that a conversation that takes place at a hearing loop-enabled counter will be overheard by other hearing aid wearers in the room.

This is the international symbol that communicates a space is equipped with a hearing loop and that a person can activate the T-mode in his or her hearing device for a clearer listening experience.

One-to-One Speech Transfer Systems (STS)

In the United States, there are a growing number of counter types that now separate employees and customers with a glass barrier. Transit centers, auditoriums, arenas, convention centers, convenience stores, police stations, and hospitals provide a few examples that illustrate the range of places where these security screens can be found. For people with typical hearing and people with hearing loss, the presence of a barrier, such as a pane of glass or a security screen, can further complicate communication and compromise a customer’s ability to understand what is being said on the other side of the partition.

Speech transfer systems (STS) were designed to facilitate communication between employees and patrons in these separated counter scenarios. An STS is a two-way communication system that offers a microphone and speaker to both the staff member and the customer, amplifying the audio signals on both sides of the glass. There are several types of these systems that offer various levels of signal clarity and different performance features. While some of these systems project poor-quality audio signals that sound muffled or tinny and can be difficult for even people with typical hearing to understand, others transmit cleaner and clearer audio signals that are much easier to distinguish from one side of the barrier to the other.

Unfortunately, for the people with hearing loss, the general amplification of sounds, or the amplification of sounds in an already noisy space, can do little to improve the overall intelligibility of a conversation because their hearing aids and cochlear implants also amplify all of the sounds in their immediate environment. Some of these systems have been designed to better support the needs of people with hearing loss by featuring a hearing loop. These systems mount a hearing loop aerial under the counter or to the glass and transmit the audio signal from the staff member’s microphone directly to the customer’s activated hearing device, eliminating much of the background noise and sound-quality issues often created by the amplification system. This better, clearer communication enables the person with hearing loss to more easily interact with the person on the other side of the barrier and improves the overall customer experience during the interaction.

Another important feature to look for in an STS solution is open-duplex technology. Open-duplex technology allows customers and staff to speak simultaneously without clipping the speech of either party, making clear communication through the security screen or pane of glass easy.

The Use of Hearing Loops in the United States

The 2010 Americans with Disabilities Act (ADA) Standards for Accessible Design (2010 ADA Standards) requires that assembly areas are hearing accessible and assistive listening systems are available. It identifies FM/RF, IR, and hearing loop systems as viable options for compliance. When FM/RF or IR assistive listening systems are used, the 2010 ADA Standards do specify the number of FM/RF or IR receivers that are required to be present in an assembly area based on the seating capacity. For example, venues with 1,001–2,000 seats are required to have a minimum of 35 receivers, plus one more per every additional 50 seats over 1,000 found in the arena.

While not explicitly required by the ADA, municipalities are taking notice of the number of people living with hearing loss and the benefit that hearing loops can offer them, increasing the availability of hearing loop technology in airports, public transit areas, and assembly areas. In 2017, hearing loops were installed on the train platforms and ticket windows in the Bay Area Rapid Transit (BART). The New York Transit Authority has installed hearing loops at more than 600 New York City subway information booths and fare kiosks, and several Taxis of Tomorrow now include hearing loops inside the cabs. Hearing loops will soon be found in many other spaces around the Big Apple, as New York City recently approved legislation that now requires hearing loops in new or renovated public assembly areas.

Several grassroots campaigns conducted by advocacy groups, such as the Hearing Loss Association of America (HLAA), can also be credited with the increasing presence of hearing loops in public performing arts centers, churches, and other assembly areas throughout the United States. For more information about the Get in the Hearing Loop (GITHL) programs, visit www.hearingloss.org.

The Key to Professional Hearing Loop Installation: Meeting the IEC Standard

Hearing loops are an incredibly flexible solution for improving the hearing accessibility of a space. As previously described, these systems can be installed in large areas that serve many simultaneously and in smaller areas where one-to-one communication occurs face-to-face or through glass. They can be installed in new and retrofit projects. Wherever they are being incorporated, the performance of a hearing loop system is largely dependent on its design and skillful installation.

Counter loop systems are constantly on and work within a defined area, protecting the confidentiality of a conversation that occurs within the hearing loop space.

The International Electrotechnical Commission (IEC) specifies strict requirements and performance standards for hearing loop systems. The IEC performance standards ensure that the system is delivering optimal sound quality and providing a positive experience for the people with hearing loss who will be using the system.

There are two unique standards that inform the design and installation of a compliant hearing loop system. The technical requirements of the hearing loop system are located in IEC 60118-4. This standard establishes appropriate measuring methods and target values to ensure that the hearing loop systems deliver the correct signal strength to the audience. IEC 62489-1 provides guidance on the methods for measuring and specifying the performance of the various system components, including amplifiers, microphones, and playback equipment.

It is recommended that the design and installation of hearing loop systems be entrusted only to qualified and trained personnel who are experienced in the specific type of application where the hearing loop is being installed. These professionals are trained to install hearing loops in a way in which the performance of the system will ultimately satisfy the IEC standard.

Conclusion

When comparing the performance of the FM/RF, IR, and hearing loop systems for large venues or counter applications, the hearing loop offers the attendees with hearing loss the most inconspicuous and user-friendly solution. Hearing loop systems also enable users to continue to hear the customized sound produced by their hearing aids instead of the loud but potentially garbled audio from public-use headphones. The convenience and overall better sound quality may explain why hearing loops regularly win the highest marks when compared with other assistive listening systems. These systems are also easier to maintain than the FM/RF and IR systems that require staff to keep track of and maintain extra parts and pieces.

When designing a large assembly area or a bustling commercial space where communication occurs, consider incorporating a hearing loop into the project to make it easier for those with hearing loss to participate in the conversation, conduct their business, or enjoy the show they are attending. It’s an effort that the community with hearing loss will hear loud and clear.

End Notes

¹Brookshire, Bethany. “How Brains Filter the Signal from the Noise.” Scicurious. 29 April 2014. Web. 2 January 2019.

Jeanette Fitzgerald Pitts has written more than 50 continuing education articles for Architectural Record covering a wide range of products and practices.