Proving the Business Case for the Internet of Things

On Semiconductor module links hearing aid to smartphone

Steve Rogerson
November 3, 2015
On Semiconductor is introducing a wireless module to allow hearing aids to be controlled by a smartphone as well as letting the phone stream voice and data direct to the hearing aid. The Arizona-based company is also launching a power management unit that will let hearing batteries be recharged.
The HPM10 is a power management integrated circuit (PMIC) and the Ezairo 7150 SL is a wireless-enabled audio processor.
“Hearing aids are a mystery to some,” Marcus Niklaus, On Semiconductor’s director of hearing products, said last month at the launch in Munich.  “Lots of people have hearing impairments but it is only a small growth. It is a stable market.”
But he said the ageing population could soon change that as more of the baby boomer generation hit retirement age; 30 per cent of 65 to 74 year olds and 47 per cent of those aged above 75 have hearing impairments.
There are two types of hearing aid – one that is worn behind the ear and the other that is inserted. The inserted types have to be customised to the wearer and are this more expensive, and account for less that a quarter of the market.
“The move now is for them to be controlled by a cell phone, but also for them to have intelligence so they can adapt to the sound environment,” said Niklaus. “On Semiconductor is the leading supplier of silicon for the hearing aid market. Sometimes customers come to us and say this is what we want to do, but we also have standard hearing aid modules.”
The Ezairo 7150 SL uses the company’s digital signal processing (DSP) technology and brings wireless connectivity to hearing aids and cochlear implants. The compact hybrid module is based on the Ezairo 7100 open-programmable 24bit mixed-signal DSP platform. This system-in-package provides wireless multi-protocol operation and is optimised for 2.4GHz band applications, including Bluetooth Low-Energy (BLE). It integrates a low-power 2Mbit serial CMOS EEPROM for storing hearing aid firmware and important parameters.
To simplify and accelerate the development process, the company has provided a complete reference design of a behind-the-ear (BTE) hearing aid. The reference design includes software, hardware and firmware, which enable advanced wireless features. The control over BLE function allows hearing aid users to control an array of parameters from their smartphone.
“We have reference designs for this,” Niklaus said. “We have boards that can be hooked up to a PC and we have development tools for those who want to use it as a base to design their own products.”
The user can adjust the hearing aid’s volume, make programme changes, check the battery status and receive phone alerts, such as incoming calls or text messages. It also has a find-me function to help users quickly locate a misplaced hearing aid. The stereo audio streaming protocol enables music to be streamed from any external audio source such as smartphones, tablet computers and televisions through a remote dongle. The connectivity range can reach up to 10 meters in good surrounding conditions.
This, said Nilklaus, could also allow the incoming voice during a phone call to be transmitted direct to the hearing aid. This facility is already available through Apple iPhones.
The PMIC provides a way to recharge batteries in hearing aids and hearing implant devices. Most hearing aids are not rechargeable today but use disposable batteries that last from four to twelve days. The batteries also can be fiddly to replace.
“Broken battery compartment doors is the number one reason for hearing aid returns,” said Niklaus. “We now have a chip that can be put into the hearing aid that lets the user recharge the hearing aid.”
It generates the voltage needed by the hearing aid and manages the charging algorithms such that the battery autonomy and the number of charging cycles are optimised. The rechargeable chemistries supported include silver-zinc (AgZn), and lithium-ion (Li-ion). It also detects zinc-air (Zn-air) and nickel metal hydride (Ni-Mh) batteries but doesn’t charge them.
During operation, power regulators help reduce lost power from the battery to the hearing aid. A built-in charger communications interface can pass data to the hearing aid charger during the charging process. Battery parameters such as voltage levels, current levels, temperature and different forms of battery failures can also be communicated. Different charging parameters, representative of battery size and type, can be stored in the on-chip one-time programmable memory.