scale, the possible situations where hearing assistance is needed may be determined. The results of the latest MarkeTrak IX survey showed an increased satisfaction with hearing aids (from 74% to 81%) and a decreased number of in-the-drawer hearing aids (from 12% down to 3%) relative to MarkeTrak VII (Abrams & Kihm, 2015). It is possible that this is related in part to the hearing aid being used for more than just amplification as connectivity options have expanded over the past 10 years.

It is interesting to note some historical influences on the terminology. Vaughn, Lightfoot, & Arnold (1981) argued that the advent of smaller hearing aids resulted in certain communication limitations and that it was imperative that greater attention be focused on communication centered environments and effective listener and talker devices. As the industry moved toward smaller hearing aids, the distinction between hearing aids and other devices such as hearing-assistive technology developed. There evolved a focus on fitting hearing aids by the audiologist and assistive technology received less attention in clinical practice. The technology became so separate, in fact, that in 1982, the notion of an Assistive Device Demonstration Center was recommended (Fellendorf, 1982). Nearly 15 years later, Sandridge and Lesner (1995) encouraged audiologists to no longer ask whether to provide assistive listening devices (ALDs), but rather to ask how to incorporate ALDs within one’s service delivery. Wayner (2004) was probably the first to recommend that assistive technology be considered part of the fitting process. It was an underlying belief that most persons with hearing loss could receive some benefit from amplification and that hearing aids were only one of a number of devices for successful rehabilitation and improved communication. Now, the connectivity options with hearing aids are viewed as a major “door opener” for the person with hearing loss (Leavitt et al., 2016). Hearing aids are capable of receiving signals from remote tablets, cell phones, and microphones. Therefore, the notion that assistive devices are a separate category that require a special focus in an audiology practice may disappear. To explore these benefits with patients, an audiology practice does not need a separate room with examples of HATS to demonstrate benefits available for phone conversations, television, or alerting signals like those recommended in the past (Wayner, 2004). In fact, the most basic wireless connectivity in hearing aids that existed even in analog hearing aids, i.e., the telecoil also known as t-coil, is now joined by an array of wireless protocols including near-field magnetic induction, 2.4 GHz Industrial Scientific Medical (ISM) band, and 900 MHz ISM band. Regardless of the sophistication of the technology or programming options, the basic process for obtaining and successfully using D-HATS remains the same. Initially, there must be an assessment of the communication difficulties that will lead to recommendations. There must be verification of the technology to document appropriate settings and, finally, validation must occur to ensure that the user receives the intended benefits. To summarize the benefits of meeting an individual’s HATS needs when devices are moving from analog to more digital options, lighthearted illustrations are provided in Appendices 21–A and 21–B. Of course, the overall challenge is to integrate these steps into the routine clinical practice, much like checking one’s blood pressure during a physical exam, so that D-HATS are considered a continuum of options from a single personal device to a network of devices and apps to address communication of both verbal and nonverbal signals. Before a review of the assessment, verification, and validation of D-HATS, a discussion of the major wireless transmission protocols will provide a foundation upon which to compare the various wireless technology options. These range from longstanding methods such as magnetic induction (telecoils) to more recent very high-frequency protocols (Bluetooth Low Energy, LE).

Wireless Transmission Protocols

A variety of wireless transmission protocols have been used to benefit those with hearing loss. These include magnetic induction, low-frequency radio signals such as near-field magnetic induction (NFMI); midfrequency radio signals such as FM 72–76 MHz, 216–217 MHz, and 900 MHz; and high-frequency transmission 2.4 GHz Bluetooth, Bluetooth LE, and proprietary protocols. All wireless transmissions have a transmitter and a receiver. How the audio signal from the transmitter gets to the receiver defines the type of wireless system.

Electromagnetic Transmission

The oldest wireless system used by those with hearing challenges involves electromagnetic transmission, which has been in use since the late 1930s. The first wearable hearing aid that contained an induction receiver, i.e., a telecoil, was reported to be the Multitone VPM in 1938 (Bauman, 2015). In an induction loop system, an audio signal from a source such as a microphone creates an electromagnetic signal that induces current to flow through an induction receiver such as the telecoil in a hearing aid. The transmission is direct rather than depending on a carrier signal. Therefore, there is no tuning required but simply positioning the induction receiver, i.e., hearing aid with a telecoil, within the induction loop. The distance from the telecoil to the loop needed for adequate transmission depends on the strength of the electromagnetic signal. Some are low-level such as a loop worn around one’s neck that transmits a signal to the telecoil in the hearing aid from a receiver attached to the neck loop. A room loop, however, is a much stronger electromagnetic field that may be installed in the ceiling or floor; thus, one may be sitting several feet from the actual loop. The signal is universal in that any manufacturer’s hearing aid with a telecoil can receive the induction signal from a loop.

Despite the simplicity and generally low cost, there can be several negative effects of telecoils such as spillover of the signal from adjacent room loops and the pickup of stray electromagnetic energy from power lines, computer monitors, and even some smart watches. Furthermore, signals transmitted via telecoils tend to be noisy, have reduced low-frequency energy relative to the original signal, and vary in intensity with head movements (Thibodeau, McCaffrey, & Abrahamson, 1988). Because of the universality of telecoils, there is a significant movement to have loop systems installed in many public areas throughout the U.S., hence efforts have been called “Loop America” or “Time to Loop America”. These efforts include web-based resources that allow the visitor to learn about loops and find public venues, such as churches or theaters, that are looped for the hearing impaired. The symbol used to alert the public of loop systems is shown in Figure 21–1.

FM Transmission

Perhaps the next significant advancement in wireless transmission was the use of frequency-modulated (FM) transmission. In FM systems, the signal from the audio source is transmitted via a carrier frequency, such as 72–76 MHz or 216–217 MHz. This carrier frequency can be selected by the user on either a wideband or narrowband range of frequencies. For example, a wideband carrier frequency may be 72.1000 MHz to 72.1250 MHz and designated by the manufacturer as Channel “A” and a narrowband carrier frequency may operate on 216.0125 MHz to 216.0375 MHz and be designated as Channel “1.” The signal of interest picked up by a microphone is used to modulate the frequencies of the carrier wave in a pattern to correspond to the original signal. The receiver must be tuned to the same channel so that the transmitted FM signal can be demodulated to recover the original signal.

The first FM receivers operated on wideband carrier frequencies and were body worn. In 1996, FM receivers were introduced into behind-the-ear hearing aids, which were limited to receiving only one or two channels and had somewhat cumbersome antennae. With advances in technology, the transmitter microphones became more sophisticated with noise reduction and directional pickup techniques, which resulted in significant improvements in speech recognition in noise (Thibodeau, 2010). Furthermore, the receivers became small enough to be attached to most behind-the-ear hearing aids with a connector called an audio shoe. The audio shoe is specific to the manufacturer of the hearing aid, but all have the universal 3-pin Euro plug to accept the miniaturized FM receiver. One manufacturer has designed receivers that integrate with their specific behind-the-ear models so that it always remains on the hearing aid.

Because the transmission range is generally about 1 meter, NFMI may also be used to send signals from an intermediary device that can be small enough to fit in one’s pocket or can be connected to a loop worn around the neck, as shown in Figure 21–2. These intermediary devices are called streamers, so as not to be confused with induction loops. Although both can be worn around the neck and communicate with the personal hearing aid, the induction neck loop requires a universal telecoil in the aid so it can be used with an aid by any manufacturer. However, the streamer requires a hearing aid with NFMI capability by the same manufacturer. Superior to the induction loop, the streamer allows for greater consistency of the signal across the frequency range and with head movement.

The streamer is ideal for housing other wireless receivers that require greater power and space than can occur within an ear-level hearing aid, such as a 2.4 GHz Bluetooth connection to a cell phone. They can even be interfaced with FM or digital-modulated (DM) receivers for streaming signals from FM/DM wireless microphones to one’s hearing aids. Because the NFMI streamer can act as a receiver and a transmitter, it is important to use clear terminology with clients about wireless transmission. Most streamers are capable of connecting with cell phones through Bluetooth 2.4 GHz universal protocol, but they transmit the audio information via a NFMI proprietary protocol to the hearing aid.

900 MHz Transmission

To avoid some issues with NFMI such as the limited transmission range, wireless transmission protocols on the 900 MHz frequency band were developed for long-distance audio streaming that could operate on typical hearing aid power levels. Starkey developed this protocol in 2012, called SurfLink, to allow hearing aids to connect directly to a television or other media source up to 20 feet away without any intermediary device on the user. The hearing aid can be programmed to detect the 900 MHz signal so that no pairing is necessary. Users can enter a living room and automatically hear the television if it is connected to a SurfLink 900 MHz transmitter. The 900 MHz transmission protocol has also been used to transmit signals from remote microphones that can be worn by a communication partner in noisy environments. In addition, the SurfLink family of accessories includes a device that can establish a Bluetooth connection with a cell phone and then transmit the call to the hearing aid via the 900 MHz protocol. It is important to recognize that the line of hearing aids compatible with SurfLink are different than the “made for iPhone” aids described in the next section although they both allow for wireless phone communication. Recall that the hearing aids compatible with SurfLink require communication with the 900 MHz transmitting device, which provides the wireless connection to cell phones through the Bluetooth protocol described next.

The first aids that were capable of communicating with cell phones through Bluetooth LE were announced by G. N. Resound in 2013, referring to them as “made for iPhone” or MFi aids. At this time, there are seven manufacturers that have hearing devices that communicate directly with cell phones without an intermediary device as shown in Table 21–1. This means that persons can send and receive phone calls and stream audio signals from Bluetooth-enabled devices that are paired with their hearing aids.

As the name implies, the MFi aids only work with Apple products. Given that 88% of cell phones sold as of 2018 were Android phones (Statista, 2019), there was certainly a need for direct wireless connectivity to these products. In 2017, Phonak announced a new protocol based on a proprietary chip that allowed pairing with Apple or Android phones (Hearing Review, 2019). The SWORD chip allowed running protocols in parallel so that the chip allowed connectivity to the hearing aids and compatibility with both Bluetooth LE and Bluetooth Classic protocols. The hearing aids with the SWORD chip were referred to as “made for all” or MFA aids. However, unlike the MFi aids, the connection was only between the phone and a single designated hearing aid. In 2019, bilateral phone connection to both iPhone- and Android-based phones was possible in the MFA aids by sending the signal from the connected hearing aid to the second hearing aid via NFMI (Figure 21–3).

Although a great solution for wireless connectivity to cell phones that are typically close by but not in the same room as the listener, the Bluetooth protocol is not ideal for transmitting in face-to-face conversation because the transmission delay can be more than 100 ms. Therefore, other digital protocols utilizing the 2.4 GHz band for wireless transmission of signals to aid those with hearing challenges were developed. In 2013, Phonak introduced a proprietary adaptive digital wireless transmission technology called Roger, where audio signals are digitized and coded in small bursts that are transmitted repeatedly in the 2.4 GHz band. This is known as frequency hopping, which avoids interference issues and has audio delays less than 25 ms. Unlike Bluetooth receivers, Roger systems have an unlimited number of connections and wider transmission bandwidths up to 7300 Hz. The Roger transmission protocol allows hearing aids to be connected to coordinated receivers; thus, the user benefits from improved wireless reception from remote microphones and other audio sources hardwired to Roger transmitters such as tablets, televisions, and MP3 players. Roger systems may also be referred to as DM systems in contrast to the older FM systems.

There is a variety of assessments that evaluate the communication difficulties facing a person with hearing loss. One common, efficient tool is the Client Oriented Scale of Improvement (COSI) (Dillon, James, & Ginis, 1997). This assessment is particularly useful because the individual provides the five most difficult communication situations, which are rated before and after amplification. Although this and other scales, such as the Abbreviated Profile of Hearing Aid Benefit (APHAB) (Cox & Alexander, 1995), are very helpful in documenting the benefits of amplification, they only indirectly evaluate the need for D-HATS. There are no questions to prompt exploration of hearing alarms like the smoke detector or alarm clock. In addition, traditional scales do not assess one’s knowledge of laws that provide these accommodations in hotels while traveling. A tool that was developed in a convenient format for the audiologist to use with every client to ensure a comprehensive assessment of communication needs is known as the TELEGRAM. Tools are most useful if the name in some way implies their function. In this case, the novel acronym was chosen to convey the desire to improve communication across distances. The TELEGRAM was designed to be completed following the routine audiologic evaluation (Thibodeau, 2004). As shown in Figure 21–4, the TELEGRAM is intended to be a prompt for the areas that must be considered: Telephone, Employment, Legislation, Entertainment, Group communication, Recreation, Alarms, and Members of the family. Obtaining information regarding one’s functioning in each of these areas will lead to recommendations for HATS or other rehabilitative strategies. The questions provided in Table 21–2 were based on critical areas recommended by Ross (2004) to be explored with every patient. Associated rating scales are suggested to quantify the difficulties. By providing a graphic form that is analogous to the audiogram, the audiologist should find it easy to document a patient’s current functioning and determine areas of need. Symbols are provided at the bottom of the form with room where items unique to each client can be added. These can represent the patient’s specific situations, such as his/her recreational preferences. For example, the degree of difficulty with phone conversations can be recorded on a range from 1 (no difficulty) to 5 (great difficulty), with an “L” for landline phones and a “C” for cell phones. Based on the difficulty, a recommendation may be made for intervention. At the next evaluation, the degree of difficulty may be compared to the initial levels to determine if improvement has occurred.

The answers on the TELEGRAM may be used as guides to determine appropriate technology. To review the possible D-HATS options, each section of the TELEGRAM will be presented relative to the possible solutions that might be used to reduce activity limitations. Although there is some overlap among the areas, use of the TELEGRAM helps to address all aspects of communication difficulties. While it is not within the scope of this chapter to review all possible D-HATS, the descriptions of various options will be provided. Many of the same considerations in selecting technology apply whether considering analog or digital options: individual needs, age, family support, familiarization with technology, current amplification features, and preference (Garstecki, 1988; Holmes et al., 2000; Leavitt et al., 2016). However, for selecting D-HATS one must also consider the individual’s experience with digital technology including smartphones, tablets, and computers. Because the focus of this discussion will continue with D-HATS options, limited discussion of common A-HATS is provided. Resources to obtain HATS are provided in Appendix 21–C so that current information regarding federal and state programs may be obtained when considering solutions for a particular individual’s needs.

When considering options for telephone communication, one must account for the fact that 95% of Americans now own a cell phone of some kind. The ownership of smartphones is now up to 77% from 35% in 2011 (Pew Research Center, 2019a). This increase even applies to the use of technology by baby boomers, among whom usage has increased from 25% in 2011 to 67% in 2018 (Pew Research Center, 2019b). However, it is still important to distinguish problems with landline phones versus cell phones because the solutions may vary depending on the features of the personal hearing aid. For example, difficulty with landline phones may be addressed by a phone amplifier or by increasing the gain of the telecoil, whereas difficulties with cell phone communication may be addressed by setting up direct audio input or a Bluetooth connection. Several resources for solutions for phone communication are provided in Appendix 21–D.

For someone with mild communication difficulties on the landline phone who does not wear hearing aids, a simple phone amplifier that fits over the handset may be sufficient. Others may need a phone that provides an amplified handset or a visual indicator. The design features of the phone, such as cordless or large numbers, will need to be considered relative to the patient’s needs.

Persons with MFi and MFA hearing aids will most likely use the connectivity features to enhance phone communication. The seven manufacturers shown in Table 21–1 provide devices that are capable of direct connectivity to phones through the 2.4 GHz transmission protocol (either Bluetooth LE for the iPhone connectivity or proprietary protocol for the Android connectivity). This feature is available in styles that fit behind or in the ear. Some of these are rechargeable and/or have a telecoil option. Unlike using a landline phone with older hearing aids, these MFi and MFA hearing aids that communicate wirelessly with smartphones allow bilateral reception of the signal from the phone, resulting in significantly improved speech recognition (Picou & Ricketts, 2011).

For those users without direct cell phone connections, the next consideration might be the acceptance of a body-worn connection to the cell phone, such as an induction loop that can interface with a telecoil in the aid or a proprietary streamer. These options will involve remembering not only to wear the accessory but also to charge it regularly. Each of these can connect to a smartphone via the classic Bluetooth protocol and have the option for increasing volume of the signal from the phone. The phone must be paired with the neck loop device to establish communication, which is a short process of turning both devices on and following “seeking” instructions on the cell phone. When paired, the audio signals from the cell phone will be sent to both hearing aids.

If the TELEGRAM assessment indicates difficulty hearing in noise, then a system with a remote microphone might be considered; such a device can be paired via the classic Bluetooth protocol to convey phone communication directly to the hearing aid, as shown in Figure 21–5, or to a neck loop or receiver connected to a hearing aid or cochlear implant. Although these microphones also require a dedicated charging cord, some have charging docks that can be interfaced with the television to send the audio signal to receivers on the hearing aids while charging.

Stay updated, free articles. Join our Telegram channel

Join