How Google's custom Bluetooth for hearing aids paved the way for improved audio quality and battery life in headphones

Virtually the same audio quality with a smaller impact on battery life? Count me in!

When Android 10 launched two years ago, one announcement may have gone almost unnoticed amongst all kinds of flashy new features: Google introduced support for direct Bluetooth LE audio streaming for hearing aids, or ASHA for short. The protocol is more focused on energy-saving than regular audio Bluetooth without trading any of the audio quality, which is important for in-ear devices that are used up to 18 hours (and sometimes even more) during a single day. This technology has also paved the path for Bluetooth LE Audio, a new universal standard that is just now making its way into the best wireless earbuds and phones.

To learn more about the state of Bluetooth, I sat down with representatives from GN Hearing, Widex, and Whisper, three manufacturers that are a driving force behind hearing aid innovation. While you may not have heard about GN Hearing before, it's part of the same company as Jabra, which is where you'll find cutting-edge hearing aid technology trickling down into consumer products like true wireless earbuds. Whisper, on the other hand, is an AI-focused startup that wants to innovate hearing aids using machine learning. While Whisper still supports standard Bluetooth, GN Hearing and Widex have already gone full Bluetooth Low Energy streaming on its hearing aids — in fact, GN Hearing co-developed the custom Bluetooth protocol with Google.

GN chief audiology officer Laurel Christensen explains that ASHA was created from a big challenge presented by standard Bluetooth. Hearing aids need a lot of processing and battery power to enable the features someone hard-of-hearing expects — noise and feedback reduction and a directional system that helps users locate sounds, all of which take up a lot of energy. "We have to think about power consumption from that perspective. We want to use the least amount of power that we can to actually do the streaming for music and for telephone calls." That's where the Bluetooth Low Energy-based ASHA protocol comes in. ASHA is much more energy-saving than the standard Bluetooth usually used for audio, enabling all-day battery life even when introducing streaming on top of all the other audio processing.

Laurel Christensen thinks that Bluetooth Low Energy streaming is the future, even if not all Android phones currently support the technology. While limited compatibility was and still is a problem, it’s likely that almost all, if not all, Android phones will work with it in the future. The company tackled the issue by working with manufacturers to ensure that high-end models would be the first to receive compatibility. "You have your high runners, such as the Samsung Galaxy S series. And that's the approach we took when working with different phone manufacturers, trying to be there with the highest runners so that we can be there for most people." After all, flagship phones are usually the ones to sell best, despite the high cost.

One big issue with ASHA is the fact that it doesn't support sending audio back from hearing aids to phones, as Jan Linden, Head of Engineering at Whisper, the company that decided to stick with regular Bluetooth audio, notes: "Only streaming to the earpiece from the phone is supported and hence the user has to hold up the phone close to their mouth while speaking." That's one reason why Whisper still uses standard Bluetooth. "We at Whisper decided to leverage that we already have an existing device, the Brain, that can be used as an intermediary for classic BT streaming from the phone. The phone sets up a classic BT connection to the Brain and the brain relays the audio to and from the earpieces using our low power proprietary protocol." This allows the company to rely on a single protocol to connect to both Android and iOS devices (which have their own, separate 'Made for iPhone' hearing aid Bluetooth protocol), which is "very attractive for a small team like ours."

That's a special case for this company, though, and Linden acknowledges as much: "In practice, this means that for direct streaming from Android mobile devices to earpieces ASHA is the only realistic option."

Linden has another point of contention, though. Even though GN's Christensen says that there's "really no quality trade-off to go with Bluetooth Low Energy," Linden maintains that "the audio quality is slightly lower due to the data compression method used." The truth is likely somewhere in the middle, and the question is if the added compression really diminishes the listening experience too much for anyone compared to regular Bluetooth.

All that considered, Whisper's Linden would rather like to skip Google's and Apple's custom solutions and is looking forward to using another new standard: "We are very excited about the new Bluetooth LE Audio that promises one standard for all devices and significantly improved audio quality for direct to earpiece streaming."

Widex, the third manufacturer I reached out to that only recently introduced compatibility with ASHA, agrees with Whisper: "We have implemented the ASHA protocol which is supported on the BT Low Energy protocol, as this would allow us to update HA devices in the field, including those that do not have BT Classic support. We still believe that the BT LE is the future for small and power-efficient devices."

This new Bluetooth standard, first proposed in 2020, is already supported in Android 12, but virtually no phone or headphone works with it just yet, not to mention hearing aids. That's because Bluetooth radios need to be built specifically with the new standard in mind, which is something that will take a couple of generations. But the standard basically takes what made the ASHA and Made for iPhone solutions so great — reduced energy consumption while maintaining almost the same level of audio quality — and makes it available for all consumers. It’s the perfect example of how technology developed for medical needs makes it into the mainstream at a much lower cost and with broader support.

Bluetooth LE Audio, on top of natively working with hearing aids (including phone call support), is supposed to enable better sound quality at a lower bit rate, making it easier to create more enduring headphones or, where battery life is currently already satisfactory, even smaller form factors. The new standard will even enable quality-of-life improvements like universally supported broadcast sessions so you can listen to some music or a film with a friend or your partner, each with their own pair of headphones.

You might think that this makes both Google's and Apple's hearing aid solutions useless and redundant on the spot, and you might wonder why manufacturers couldn't just wait for the new standard to manifest instead of bothering with a solution of their own. While this could be said for virtually any technological advancement, Google's hearing aid protocol did bring a better audio experience to thousands, if not millions, of hard-of-hearing people long before we'd even ever heard rumors about Bluetooth LE Audio. It's also more than likely that the same companies that have pioneered ASHA and Made for iPhone, like GN Hearing, also actively worked with the Bluetooth standard body to introduce this new LE solution — after all, the company will benefit from it as a headphone manufacturer. All of the involved parties probably bring in all the experiences and issues they've run into with Apple's and Google's protocols into the process, too, making sure not to repeat mistakes.

ASHA and Made for iPhone also enabled a few hearing-aid-specific options long before they’re making their way into the Bluetooth LE Audio standard. Using the protocols, you can tweak your hearing aid settings and preferences right now on your handset, like only enabling one hearing aid for streaming, tweaking if the aids should always ring for phone calls, and more. The Bluetooth LE specification for these capabilities, Hearing Access Profile and Service, are still only in draft form.

In any case, Bluetooth LE Audio is a standard to look forward to, regardless of whether you're hard of hearing or not. It will be much less taxing on your headphones, earbuds, or hearing aids, and without all the legwork done by GN, Google, and Apple, the introduction of the new standard might not have come so quickly and might have not been so all-encompassing.

All that said, I am very much looking forward to the future of Bluetooth. Maybe it will soon really be time to retire the headphone jack once and for all.

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