Understanding Auracast: Q&A with Jeff Solum, Wireless System Architect at Starkey

Bluetooth^® Low Energy (LE) Audio has been designed as the new gold standard for Bluetooth audio streaming. Able to stream more efficiently, with fewer drop-out rates and better performance than its Bluetooth predecessors, LE Audio was developed to solve many hearing aid streaming issues.

Numerous hearing aid manufacturers now employ Bluetooth LE Audio. In October, Starkey launched its Edge AI and StarLink Edge AI TV Streamer, which are both Bluetooth LE Audio compatible and Auracast™ ready.

HearingTracker thought it would be interesting to interview with Starkey’s Jeff Solum, who has been the company’s Wireless System Architect since 2004. Solum also led the hearing aid working group within the Bluetooth Special Interest Group (SIG) that is responsible for bringing LE Audio to market.

HearingTracker (HT): Can you tell us about the Bluetooth Special Interest Group (SIG) and your work with it?

Solum: The Bluetooth SIG is a nonprofit organization that's formed from member companies interested in short-range wireless technology. They’re responsible for making things work together in a wireless way.

Currently, I'm the chairman of the hearing aid working group, and I've been involved with Bluetooth SIG for the last 14 years or so.

HT: I’ve heard you even received an award from the SIG?

Solum: Yes, I received the leadership award last year for my role as chairman of the hearing aid working group and was nominated for the Innovator of the Year Award for the papers and technical contributions I've made.

HT: Congratulations! Let’s talk about Bluetooth LE Audio. What exactly is it?

Solum: Thank you. The “LE” in Bluetooth LE stands for Low Energy. One problem with Classic Bluetooth was that it required extra power to operate, and there was also no way to send audio to more than one device at a time. Bluetooth LE is low energy, meaning it has longer battery life. It will last a full working day without problem.

Because most people have two hearing aids and because they're not connected by a wire, we needed a way to send simultaneous audio to both devices. We also developed a broadcast mode on top of it so we could send audio to an unlimited number of people within range of a transmitter.

Q. Where does Bluetooth technology actually reside inside a hearing aid? Is it inside the main processing chip or on a separate chip or module, and does this make any difference?

Solum: The Bluetooth radio is a separate chip that interfaces with the main processor over a high-speed serial bus.  Within the radio, there are three microprocessors that control the Bluetooth communication and LC-3 codec processing.

C-3 stands for Low Complexity Communication Codec, which is a highly efficient audio codec [a tool for compressing or decompressing data] designed for Bluetooth audio streaming and is a key component of the Bluetooth LE Audio Specifications.

Q. How is Bluetooth LE better than previous Bluetooth versions?

Solum: The sound quality improved significantly. When you look at the quality of Bluetooth LE Audio, it's far superior to previous versions. It runs at about half the bit rate, so it uses much less energy because the packets are so much smaller, and yet it still has a far superior signal quality.

It’s also more robust. One neat thing about Bluetooth LE versus Classic Bluetooth is that it can infinitely trade off latency for wireless quality. There is interference out there, right? For example, there's Wi-Fi that's on the same frequency band as Bluetooth, but we have collision-avoidance mechanisms built into the protocol so that we're frequency-hopping; we're avoiding channels that are interfered with. But we also have retransmissions, and we can design the number of those retransmissions to be dependent on the latency that we're trying to achieve or the quality.

Q. Let’s talk about Auracast. Can you explain what it does and provide us with some examples where it might be helpful?

Solum: Sure. One of the things that really excited the hearing industry was this idea that we could do a broadcast with Bluetooth LE Audio—something that had never been done before with Bluetooth Classic.

Bluetooth Classic is a two-way communication: one device to another. With Bluetooth LE, we had an opportunity to employ broadcast audio. For example, you might be at a gym or health club that has numerous TVs. With Classic Bluetooth, maybe you could tune your cell phone into the TV station or broadcast via an app, but doing this is labor-intensive and hit-or-miss — practically no one does this because it’s too hard. What we're left with is these silent TVs: just talking heads with maybe some closed captioning, if you’re lucky.

Now, imagine that same health club with about 15 TVs. With Bluetooth LE, we’ve allowed the smartphone to be able to pick up the information [from the TV] and then display it in a meaningful way in a smartphone menu. So, there's metadata that's also being transmitted to tell you about the name of the broadcast, the channel you might be listening to, the content, and the language featured in the broadcast. In fact, you might have multiple languages, and those will also be displayed on your smartphone, which is connected to your hearing aids.

You'll be able to choose from that menu the content you want to listen to, then your earbuds or hearing aids will immediately go to that content, and you’ll get that audio broadcast directly. In other words, the audio streams directly from the transmitter to your hearing aids, bypassing your smartphone.

Another example might be at the airport. You're walking through the terminal, and you want information about your flight. You probably have been given some type of code when you bought your ticket, and let’s say you're authenticated with Delta Airlines Flight 213. So, you hear all about Flight 213 as you're walking through the airport. You get to the gate, and you hear about the flight status or the boarding time or any type of flight delay. Those things should be available along with the overall public announcement system for the entire airport.

One more example: My wife and I love to go skiing, and I'd like to listen to her music on the slopes because she has better music tracks. I can't do that right now, but it's coming. With Auracast and using her phone, it's possible.

Q. How will Auracast benefit the hearing industry?

Solum: For the hearing industry, it was wonderful because we could do assistive listening instead of using a telecoil, which has a very limited range and very limited fidelity with very poor frequency response. And now we can broadcast into an entire auditorium with a single device. Instead of having a physical wired loop system around a large area, which is expensive to install, you can now just put a gateway in the ceiling just like you would a wireless Wi-Fi gateway. This allows anyone with a Bluetooth LE device to listen.

Now, the broadcast assistant is something that Bluetooth SIG also invented along the way, which was a way so that the hearing aids, earbuds, or headsets don't have to constantly be scanning to figure out what to listen to.  

Q. Great information! Thank you for your time, Jeff.

A. No problem, thanks for inviting me.

To learn more about Starkey’s Edge AI and its LE Audio capabilities, please visit StarkeyPro.com or check out the LE Audio Feature Summary.