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When audio over BLE meets always-on voice activation

December 04, 2017

YouvalN-December 04, 2017

Hearables and truly wireless stereo earbuds are gaining popularity, but they are still far from reaching their full potential. These tiny devices can transform the way people interact with their surroundings, adding enhanced hearing capabilities, enjoyment, and safety to everyday life. Market adoption is already underway for a wire-free music experience. As more devices are becoming voice activated -- from home appliances to action cameras -- so too are these tiny earbuds, while at the same time the intelligence of voice interfaces is constantly increasing. However, lack of standardization and integration of the multiple technologies into one seamless package is still holding back this market.


Hearables are becoming ubiquitous, but their full potential is still untapped
(Source: Sony Mobile)

Enhanced sound from noise reduction to augmented reality
Smart earbuds allow users to enjoy a richer experience from their digital content while being in touch with their surroundings, and without being tied to a handheld device. Smart earbuds can be used to isolate, amplify, or suppress sounds in real time. For example, voice isolation powered by deep learning can allow people to comfortably converse in a noisy setting. Smart earbuds can also improve safety in loud environments, like construction sites, by selectively reducing harmful noise while keeping other sounds audible. With existing technology, users can have complete control over what outside noises can enter and how loud they will be.

To do this, smart earbuds use a wide variety of techniques to optimize the audio experience for the user. Passive noise reduction uses the physical material of the device to insulate the user's ears. Active noise cancellation listens to the noise outside and generates an anti-phase sound wave that eliminates the outside noise in the user's ears. Acoustic echo cancellation allows the device to cancel out the sound waves that it is generating, to avoid echoes getting back into the built-in microphones, and to allow barge-in of the user's voice commands. Adaptive beam forming uses an array of microphones to identify where the voice is coming from and to cancel out sounds coming from other directions. Positional audio uses psychoacoustics to generate the illusion that sound is coming from a specific direction, like in front or behind the user. In earphones, positional audio can be used to generate virtual surround, which creates the experience of surround sound while using only two earpieces. The quality of the sound is further improved by techniques like bass boost, which allow the tiny speakers in the user's ears to deliver the sound performance of a much larger speaker system.

In addition to enhanced sound, the user's experience can be further upgraded by adding augmented sound reality and sound sensing technology. Augmented sound reality combines digital sounds, like notifications or location-based announcements, with the real sounds of the user's surroundings. Sound sensing identifies sounds using artificial intelligence. The user can customize the reaction to specific sounds. For example, the user can set a warning alert for sounds that might pose a threat, like sirens, honking cars, or barking dogs.


Combining physical and digital sounds with intelligent processing creates a new audio experience (Source: Nuheara)

Virtual assistants in your ear
Hearables are not just for hearing. With the integration of voice activation technology, the earbuds can act as a portal to any cloud-based virtual assistant, like Alexa, Siri, Google Assistant, or Cortana. Always-listening devices are becoming ubiquitous, from smart speakers in the home to smartphones you can activate and control by voice only.

With in-ear devices, information can be obtained on the go, without pulling out a phone or averting your gaze. That is why it is crucial for them to integrate always-on technology. The extreme popularity of smart speakers like Amazon Echo and Google Home is due, in part, to their ease of use. A simple voice command is the only interface you need. On the other hand, hearables like the Apple AirPods need a manual tap before making a voice command. This may be trivial in many cases, but when the user's hands are occupied, like while driving, chopping a salad, or scaling a mountain, that little tap makes all the difference. Once the user's hand is required, it impedes the natural, easy interaction that makes voice activated assistants so useful.

Short battery life is the bane of hearables, but this could change very soon
One of the biggest challenges for smart earbuds is the integration. All of the technologies listed above require software, hardware, and expertise in complex acoustics. The challenge is intensified by the extremely small form factor of this category of devices, in which the goal is to make the devices as unnoticeable and unobtrusive as possible. This creates severe restrictions for size and efficiency.


Hearables combine many technologies that must be integrated efficiently into a tiny package (Source: Bragi)

All the above features wrapped in one neat package that fits comfortably in your ear is sure to be a colossal success with mass market appeal... unless the battery runs out after just a few hours. To be convenient, hearables must work an entire day or more without charging. If you're not convinced, check why Doppler Labs had to shut down, despite their amazing technology.

Today, Bluetooth Classic A2DP is the most common connectivity profile for wireless audio devices, but it has some limitations. The most substantial problem is power consumption. This is especially true for hearables, which typically have tiny batteries. Most hearables do not last longer than three hours before they need to be charged. Streaming audio over Bluetooth Low Energy (BLE) would significantly reduce power consumption, thereby allowing the same devices to last a full day or more. Currently, audio-over-BLE is not standardized and some companies have proprietary solutions. Once the Bluetooth Special Interest Group (SIG) creates a standardized profile for audio-over-BLE, this will enable multiple vendors to offer devices that will last for a full day between charges. This will propel the entire market forward towards realizing the full potential of the hearable and smart earbud market.

Learn more
Click here to discover how a light-weight DSP can enable close-to-zero-power always-listening. And click here to learn how to achieve ultra-low-power embedded Bluetooth connectivity.

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