Wearable technology has undoubtedly been the fastest growing sector of the industry in recent years. Millions of people rely on trackers like the Fitbit range to help improve their health, while smartwatches are delivering unfathomable amounts of information directly to our wrists.

There are smart running shoes that give you feedback on your technique and even yoga pants that connect to your phone via Bluetooth and give you haptic feedback while holding poses. And that’s not even mentioning the advances in virtual reality, augmented reality and now even mixed reality that can expand our horizons.

[Read more: Why you should consider a smart watch]

In the fifth part in our ‘Future of Technology’ series we’re looking at the next great expansion for smart wearable devices that brings technology back to a very familiar place: our ears.

What can hearables do?

The so-called hearables go far beyond furnishing us with our favourite tunes and handling our phone calls. They’ll bring the power of smart assistants like Siri and Google Now, fitness coaching, brain training, stress management and even real-time translation tools.

BT managing director of external innovation Jean-Marc Frangos says hearables are the next big frontier for on-body technology.

“Wireless earphones are becoming much more interesting now,” he said in an interview.

The most obvious use case appears to be in the gym, where wireless Bluetooth earphones are already are already prominent and digital coaching tools are already in use.

“Some of these now double as a pulse reader, so it can read your heart rate. It can also take people’s temperature using sensors in the earpiece,” Frangos says.

“It doesn’t take too much more to have a concierge to help you in the gym, which can also tell you to do more or less or instruct you its time to change equipment.”

[Read more: How your smartphone can look after your health]

Devices like the Bragi Dash (main pic) and Samsung Gear IconX are nascent examples of the potential for these devices to change how we work out.

The Vi hearable takes things a step further with an AI assistant that learns about your body and can adapt to your training goals over time. Users can ask what their current heartbeat, and receive a pep-talk when they’re approaching the last few feet of their run.

“Vi talks to you while you workout,” the company says. “You’ll forget that she’s an AI and think of her as a true workout companion.”

However, fitness is only a jumping off point, Frangos says. He believes hearables can become a personal concierge, regardless of your activities.

Hearables for day-to-day life

“Outside of the gym, it’s something that’s potentially permanently in your ear, acting as your closest assistant you have. It could give you walking directions with your smartphone as the companion, for example,” says Frangos.

“It’s something that’s voice driven, because you speak into it, you have Alexa or some other natural language interpretation in it, you have the power of AI in the cloud with feedback directly spoken to you as a result of what you’ve asked for or not even asked for.”

[Read more: Amazon Echo – what is Alexa]

Some of the devices already pushing the envelope include the Mymanu Clik, a pair of wireless buds that promises to translate 37 languages in real time. When someone speaks to you in a different language, you’ll simply hear the translation in your native tongue. At just £155, this could become the next must-have gadget for travellers, or people doing business overseas.

Taking things a step further, the Brainno is able to measure your brain activity using three built-in sensors. The data captured by the hearable is synced back to a phone using Bluetooth, where an app will offer suggests on reducing stress, improving concentration and achieving optimum mental health. It also offers a series of brain-training games.

With the start-up community embracing hearables as the next frontier in wearable technology, there are few limits on how far this can go.

“I think the next thing will be the implant, but I don’t want to go and try that one,” Frangos jokes.

Read more in our Future of Technology series: