Bluetooth causing you the blues?

Is Bluetooth causing you the blues? Here is self-confessed audiology nerd Peter Mulas to try and help relieve them…

Bluetooth has been a game changer in hearing aid design and function, namely due to its ability to provide direct audio streaming and remote-control functions to hearing aid wearers.

Despite the great potential Bluetooth brings, we do hear from clinicians that it has also fundamentally changed the fabric of a standard fitting appointment, which now needs to include additional efforts to ensure the client’s hearing aids properly connect to smartphones, tablets and other accessories.

In this blog I wanted to take a moment to cover off some frequently asked Bluetooth-related questions that often come up when completing training sessions with clinicians who may get stuck explaining Bluetooth or understanding how it works.

I’m sure some of you might be thinking “I’m a hearing specialist, not an IT specialist – why do I need to bother learning about this technical Bluetooth stuff?”; and trust me, you’re not alone!

However, love it or loathe it, thanks to everyone’s reliance on their smart devices, the Bluetooth connections between your client’s hearing aids and their smart devices have become just as important to their hearing aid experience as any other part of the hearing aid, so understanding Bluetooth is an important part of being a hearing specialist in 2021.

So let’s start at the very beginning, what is Bluetooth?

Put simply, Bluetooth is a technology that can connect two or more devices together, wirelessly. For many applications, Bluetooth has become the standard for wirelessly connecting devices in a comparable way to how ‘USB’ has become the standard for ports and cables.

Bluetooth devices connect using a very high frequency, 2.4 GHz, or 2400000000 Hz (yes, that’s a lot of Hz!). This puts Bluetooth in the radio spectrum; and as such is fairly short range in nature¹ and it can be blocked by walls, physical obstructions and is very effectively absorbed by bodies of water (such as the human body²).

Bluetooth is also not the only type of wireless signal that utilises the 2.4 GHz spectrum; Wi-Fi can be transmitted at this frequency as well as home cordless phone networks, computer accessories like wireless mice and keyboards; and even Phonak has a number of wireless signals using 2.4 GHz (Roger™, AirStream™ and Binaural VoiceStream Technology™). As so many devices can also use this spectrum it does mean that Bluetooth is not only susceptible to physical barriers, it can also be susceptible to interference from other technologies that utilize the same frequency range.

So, distance and interference are two key aspects to keep in mind when troubleshooting Bluetooth-enabled devices. Bluetooth devices will try to overcome these aspects by increasing the power output of the transmitting device and sensitivity of the receiving device if signal quality is poor³, or switching channels which may be less prone to interference, however there is no substitute for minimizing distance and interference as an initial strategy.

What is Bluetooth pairing?

Bluetooth device connections are initialized in a process called ‘pairing’. Pairing allows the two devices ‘to get to know each other’; they share device addresses and connection information as well as a passkey so that the process is secure and they can reconnect to each other when appropriate.

For Phonak hearing instruments, the ‘Bluetooth Classic’ connection, which allows for audio streaming, should reconnect automatically and stay connected, provided Bluetooth devices are switched on within range of each other. The ‘Bluetooth Low Energy’ connection which allows for app connectivity, will only reconnect when the myPhonak app is loaded.

Bluetooth Classic vs Bluetooth Low Energy… Isn’t Bluetooth just Bluetooth?

Bluetooth connects all sorts of electronic devices together; and while we typically focus on the connection between hearing aids and phones, Bluetooth connects many other devices together, e.g. it can connect sensors to medical equipment, keyboards and mice to computers and of course wearable technology like smart watches, to phones.

So one key take home point from this blog is that not all Bluetooth connections are the same – and this is because different information will be exchanged depending on the connection.

For Phonak hearing aids, we use two types of universal Bluetooth connections, ‘Bluetooth Classic’ and ‘Bluetooth Low Energy’. ‘Bluetooth Classic’ is an umbrella term for audio signal streaming from a connected device, and covers sound generated by a smart device including phone call signals and media signals. Bluetooth Classic signals continue to be used by the majority of all Bluetooth audio devices, including headphones, earbuds, speakers, car systems etc, so don’t be fooled into thinking it is an out of date standard – it is one of the most broadly compatible connections available.

When paired and connected, a Bluetooth Classic connection covers the streaming of phone calls and music/media type signals from a source (e.g. phone) to a ‘master’ hearing aid, which then relays audio information to the contralateral hearing aid. This is why when pairing a Phonak hearing aid for audio streaming, you’ll only ever connect one ear. It’s also important to know that Bluetooth Classic signals are very dense digital signals and carry a lot of information per second, and this is why streaming phone calls and media signals can increase battery drain.

By using Bluetooth Classic, a Phonak hearing aid is forwards and backwards compatible for direct audio streaming, for a broader range of smart devices including Android and iOS smart phones, laptops, PCs, televisions and even smartwatches.

Phonak hearing aids also support a second universal type of Bluetooth connection, Bluetooth Low Energy (LE), which allows connection to a Noahlink Wireless for programming and also provides the connection for remote control purposes, either between a smartphone running our myPhonak app or our handheld Remote Control unit. Bluetooth LE is also commonly found in smart watches and other sensor equipment, and was widely used in the development of contact tracing apps during the COVID-19 pandemic.⁴

The amount of information transferred by Bluetooth LE connections is significantly smaller than that required to stream audio and, as such, this type of connection is much gentler on battery consumption.

So the moral of this section is that not all Bluetooth connections are created equal. Bluetooth Classic connections transmit audio information (e.g. phone calls and music), offer broad compatibility and are used by many Bluetooth-enabled devices available today. Bluetooth LE connections transmit synchronization and program information, which is much smaller in content than Bluetooth Classic, and allow for remote control and wireless programming via Noahlink Wireless.

What about Made for iPhone (MFi) hearing aid technology and Audio streaming for hearing aids (ASHA) for Android devices? Do these differ from Bluetooth Classic?

Bluetooth Classic, MFi and ASHA technology have the same goal: to stream audio from a device to a set of hearing aids – however they go about it in different ways. Unlike Bluetooth Classic, which is an open, universally supported approach, MFi and ASHA enabled hearing aids use proprietary versions of Bluetooth to connect to select iPhone and Android devices.

This proprietary version is often referred to as ‘Bluetooth Low Energy Audio’ (not to be confused with Bluetooth Low Energy, which Phonak uses for programming and remote control connections).

All in all, this means:

• MFi and ASHA are closed and not universal. You can only connect these hearing aids to smart devices that support the MFi or ASHA system, which are far less in number than devices that support Bluetooth classic connections, and only limited to phones and tablets.
• Handsfree calls are not available. MFi and ASHA protocols still rely on using the phone’s onboard microphones during a phone call, which meaning the hearing aid wearer needs to hold the phone during phone calls. Phonak’s Bluetooth phone call system uses the hearing aid microphone to capture the wearer’s voice, which means phone calls are completely hands free.

Practice, practice, practice!

If you’re still feeling a little overwhelmed by Bluetooth, it always helps to practice with a set of trial hearing aids and practice broadly! While it’s quite common for clinicians to pair to their own phone, it always helps to try and pair hearing aids to other devices including other brands of smartphones, tablets, PCs and Bluetooth-enabled TVs where possible, to increase your comfort levels with different types of devices.

Don’t forget, just like the many other complicated tasks you have to master as a hearing care professional (bone conduction masking for example), Bluetooth is complicated, until it’s not. 

To learn more, we invite you to read a Phonak Insight on Bluetooth Classic for hearing aids.

References

1. Shorey, R. & Miller, B.A.. (2000). The Bluetooth technology: Merits and limitations. 80 – 84. 10.1109/ICPWC.2000.905777.
2. Werner, D. H., & Jiang, Z. H. (2016). Electromagnetics of body-area networks: antennas, propagation, and RF Systems. Wiley-IEEE Press. https://doi.org/10.1002/9781119082910
3. Marcel, J. (2019, Oct 17). 3 key factors that determine the range of Bluetooth [Blog]. Retrieved from https://www.bluetooth.com/blog/3-key-factors-that-determinethe-range-of-bluetooth/, accessed March 15, 2021
4. Pullicino, E. (2020, May 11). Coronavirus and contact tracing apps. Retrieved from https://www.lexology.com/library/detail.aspx?g=4c728a68-4bd4-4698-8b00-12ccf7a9c8ef, accessed March 15, 2021