Advanced Hearing Aids: Wearables You’ll Want to Wear

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In many wearable devices, wireless connectivity is quickly becoming more commonplace, instead of a feature found only on high-end devices. Wireless technology makes it much easier for users to control their device, ultimately helping to make the user experience more enjoyable and increase adoption. Still today, making control adjustments (e.g., volume control, program selection, etc.) on a hearing aid can be challenging. Users can make adjustments manually by selecting the one or two small buttons on the device. Some may be able to do this while it is still on the ear, but others may have to remove it beforehand. Another option requires using a dedicated manufacturer specific remote control, or a relay device (a larger unit typically worn around the neck), if operations using a smartphone are desired. Most hearing aids available today don’t possess the ability to communicate directly with smartphones, so this additional unit is needed in order to convert the proprietary radio link hearing aids use into a standard Bluetooth[sup]®[/sup] link smartphones can understand.  
 
Since many people today already carry and use smartphones, using it to communicate with and control the user’s hearing aids has by far the most appeal. Adding to its ease-of-use, custom smartphone applications feature intuitive icons and touch controls which are friendly for all levels of technical understanding. For hearing aids, these apps allow users to easily check their devices’ battery levels, and optimize program or volume control settings of left and right hearing aids individually. Other features can include alerts to incoming texts or phone calls, or the use of RSSI (Received Signal Strength Indicator) to help locate a misplaced hearing aid.
Using wireless technology, audio can be streamed digitally to the hearing aid from an external source such as a sound system or a television equipped with an ancillary device. This can provide a more immersive entertainment experience for the wearer, with better audio quality. Wireless technologies such as Bluetooth Low Energy (BLE) now provide the opportunity to deliver better and more discrete user experiences for hearing-aid wearers. Several hearing aid manufacturers have enabled BLE in their hearing aids by creating a direct radio link between the device and smartphone, eliminating the need for a relay or third-party unit.  
 
Within any hearing aid form factor(from Behind-the-Ear (BTE) to Receiver-in-Canal (RIC)), the designer must arrange the receiver, the battery and associated circuitry, user controls for volume adjustment and program switching, and the audio digital signal processor (DSP) and associated peripherals including memory and now a Bluetooth radio transceiver. One or more microphones are usually needed, to enable background-noise cancellation and directional sound pick-up. The power consumption of the additional radio subsystem must also be considered to minimize any impact on the overall system to avoid demanding a larger, heavier battery to supply more energy.


 

System-in-Package (SiP) solutions can help overcome the space limitations of miniature devices by integrating several components into a single package.
 
Designed specifically for hearing aids, Ezairo[sup]®[/sup] 7150 SL is a wireless-enabled audio processing hybrid module which can easily be integrated into a standard BTE shell. Based on the programmable Ezairo 7100 digital signal processing (DSP) platform, the miniature hybrid module features precision quad-core architecture. Ezairo 7150 SL provides multi-protocol wireless support, is optimized for 2.4 GHz license- free radio bands, and is compatible with BLE as well as custom protocol variants to deliver ultra-low-power stereo audio streams. To store important hearing aid parameters, Ezairo 7150 SL provides 2 Mb of non-volatile memory (EEPROM).
To further assist with development, ON Semiconductor has produced a complete reference design of an Ezairo 7150-SL based BTE hearing aid, including the hybrid module, required passive components, and 2.4 GHz radio antenna to help designers develop and refine their own device. The reference design is comprised of fully- assembled hardware, a sample Android™ application, and firmware for stereo audio streaming via a remote dongle and Control over BLE.



Multi-protocol wireless support enables advanced hearing aid features such as Control over Bluetooth Low Energy (CoBLE) using a smartphone or tablet, and audio streaming via a remote dongle that plugs into the standard audio output jack of the source equipment. The audio streaming protocol uses a proprietary low-latency radio link that consumes very little power (only about 4-5 mA off a standard Zinc-Air hearing aid battery).

The stereo audio streaming feature allows users to hear audio from any external source like televisions or car radios through the use of a small transmitter dongle. The dongle can also operate in remote microphone mode, further enhancing the user’s listening experience in challenging situations, like noisy environments or class rooms where the speaker might be far away.</p><p>
Advanced features, especially wireless connectivity, hold the potential to revolutionise quality of life for hearing aid wearers. Physical space constrains have been a key factor in limiting progress, but sophisticated integration techniques and new radio technologies have now helped to enable wireless connectivity, such as Control over BLE and low-latency audio streaming, without the need for bulky relay devices. These features now set the scene for dramatic improvements to the end-user experience, helping to transform hearing aids from a device someone needs to use into one they’ll want to use.