An increasingly important feature for hearing aids and cochlear implants is a means to connect directly and wirelessly to an outside sound source. For decades, this direct wireless connection could only be accomplished by using a telecoil built into the hearing device. Telecoils couple to external sound sources, such as telecoil-compatible telephones or large-area hearing loop systems like those found in some places of worship, movie theaters, meeting rooms and other venues.

In the case of telephones, the Federal Communications Commission (FCC) requires that telephone handsets be compatible with hearing aids and cochlear implants. Technical standards are used to determine if a telephone handset meets the FCC hearing aid compatibility (HAC) requirements, which include telecoil coupling capability. HAC requirements have been in place since Congress passed the 1988 Hearing Aid Compatibility Act. Over time, these requirements have been extended beyond landline phones to include, in part, wireless phones, such as today’s smartphones.

Telecoil coupling is fully interoperable across wireless phones regardless of operating system because telecoils are a non-proprietary solution. Any telephone that has telecoil coupling capability can work with any hearing aid that has a telecoil. And any hearing aid that has a telecoil can work with any telephone that has telecoil coupling capability.

Although hearing aid compatibility has become synonymous with telecoil coupling, the HAC Act is technology agnostic. The law itself does not specify that the means for accomplishing compatibility between hearing aids and telephones must be accomplished using a telecoil; rather, it encourages the use of currently available technology, which at the time the law was enacted and until only recently, was limited to telecoil coupling. 

Bluetooth Low Energy (LE) for audio streaming in hearing aids: MFi and ASHA 

In the last ten years, the use of Bluetooth for direct audio streaming of voice calls or media from a wireless device (e.g., a smartphone) to a hearing device has become much more commonplace. Apple was the first wireless device manufacturer to implement direct Bluetooth-based audio streaming in their iOS handsets through their Made for iPhone (MFi) technology.

The key to supporting this advancement in hearing aids was to address their lower power requirements. Apple did this by using Bluetooth Low Energy (LE) technology. However, at the time, audio streaming was not supported by Bluetooth LE. Consequently, Apple developed a proprietary extension that would support this capability while also taking advantage of the reduced power consumption afforded by Bluetooth LE.

MFi hearing aids can use traditional means of coupling to both iOS and Android phones for voice calling, either acoustic coupling through the hearing aid’s microphone or inductive magnetic coupling if the hearing aid has a telecoil. However, due to MFi’s proprietary nature, MFi technology in hearing aids can only be used to couple with Apple iPhones; it cannot be used to provide Bluetooth audio streaming for voice calling to Android devices.

The first iPhone to support MFi hearing aids and the first MFi hearing aids came on the market at the end of 2013. All iPhones since that time support MFi hearing aids—and a growing number of hearing aids are MFi capable.

In 2019, Google introduced their Audio Streaming for Hearing Aids (ASHA) technology in phones using the Android operating system. Like Apple, the Google solution needed to utilize a proprietary extension to take advantage of the Bluetooth LE technology. For a hearing aid to be interoperable for voice calls with both iOS and Android phones using Bluetooth LE-based technology, manufacturers need to implement both solutions – MFi and ASHA – into their devices.

Improving hearing aid compatibility for smartphones and other wireless handsets

Currently, the Hearing Aid Compatibility (HAC) Task Force, a group of key stakeholders, is working to make recommendations to the FCC on HAC compliance for all wireless handsets.

The Alliance for Telecommunications Industry Solutions (ATIS) convenes this effort on behalf of these stakeholders, including the:

• Competitive Carriers Association (CCA), 
• CTIA – The Wireless Industry Association, 
• Hearing Loss Association of America (HLAA), 
• National Association of the Deaf (NAD),
• Telecommunications for the Deaf and Hard of Hearing (TDI), and the 
• Telecommunications Industry Association (TIA).

The Task Force is collecting data about current technical and market conditions involving wireless handsets and recent innovations in hearing improvement technology. The goal is to deliver recommendations to the FCC by the end of 2022 that could serve as the basis for future FCC rules in this area. Data of interest to the task force includes:

1. What the current availability of telecoils is in hearing aids;
2. What the current availability of Bluetooth audio streaming (either Bluetooth-LE based MFi and ASHA technologies or Bluetooth Classic technology) is in hearing aids, and
3. How the availability of these various methods has changed over time. 

Wireless telecoil, MFi, and ASHA use in hearing aids over time: HearingTracker data

HearingTracker maintains a database that includes the main hearing aid brands and their technology levels from the major manufacturers. This data has been curated since 2008 and uses information from the specification sheets of hearing aid manufacturers to create a consumer tool for comparing selected hearing aids. 

While each year’s data is not exhaustive, inclusion criteria—based on market share and judgments of meaningfulness and interest to consumers—suggest that it does represent a reasonable sample of the hearing aid market (Table 1). The data primarily consists of RIC- and BTE-style hearing aids with some custom styles (ITE, ITC, CIC) which together constitute most hearing aid styles sold. 

For purposes of the task force, we looked at 10 years of data from 2012 through 2021 and a total of 806 hearing aids with release dates during that time. 

Bluetooth LE gaining popularity in hearing aids; Telecoils still prevalent

Among the major hearing aid manufacturers and their main brands found in the HearingTracker database, Low Energy (LE)-based Bluetooth as a direct audio coupling method for wireless phone calling has been steadily increasing in availability over the past 9 years since Apple’s MFi was introduced (Figure 1).

Over time, it's likely that the new Bluetooth LE-Audio solution for direct wireless audio streaming will become ubiquitous and universally used in hearing devices and wireless phones, as well as other consumer electronics devices, such as televisions, computers, and more. Over the next several years, we can look forward to another snapshot of the landscape regarding hearing aid coupling options to wireless phones and other sound sources as HearingTracker continues its database curation.

Acknowledgements

Abram Bailey, CEO of HearingTracker, generously provided the HearingTracker data to the HAC Task Force for this analysis to inform the task force’s work. Members of the HAC Task Force and Karl Strom, editor in chief of HearingTracker, reviewed and provided many helpful comments to the author.