Preconfigured DSP Solutions for Wireless Hearing Aids

    In order to meet the needs of home health care and people's increasing interest in health and wellness equipment, ON Semiconductor provides pre-configured DSP and open programmable DSP systems for hearing aids for medical applications in the Chinese market, helping Chinese medical electronics manufacturers develop innovative high-precision, reliable and low-energy medical equipment. At the same time, ON Semiconductor also provides supporting software and hardware development tools to assist customers in achieving secondary development beyond chip products, and a team of application engineers provides on-site support for customers to help them shorten the design cycle and speed up product launch.

    Nearly 12 million hearing aids are expected to be sold worldwide in 2012, driven by an aging population, longer life expectancy, lower birth rates; rising incomes in emerging markets (China, India, Brazil and Eastern Europe); and the spread of hearing loss caused by diseases such as excessive noise, diabetes, and ototoxicity (a side effect of certain prescription drugs).

    Hearing aids are mainly divided into behind the ear (BTE) and in the ear (ITE), suitable for patients of different ages and different needs. The former includes traditional BTE, mini BTE and receiver in canal (RIC); while the latter includes full, 3/4, half-cavity ITE, in the ear canal, completely in the canal (CIC) and invisible in the ear canal (IIC). There are three trends: the first is discrete and "invisible", the smaller receiver in the ear canal (RIE) and the new invisible in the ear canal (IIC) type are more popular when the American "baby boomer" generation began to adopt hearing aids; the second is wireless communication and connection: the current technology is 2.4 GHz, 900 MHz and near-field magnetic induction (NFMI) with Bluetooth relay; the third is fully automated and "intelligent", the volume control and signal processing automatically adapt to the sound environment, so it is more effective and more convenient for users. Meeting these trends requires migration to 65 nm or smaller node processes and miniaturized packaging technology; interoperability and advanced packaging technology; and increased processing power and algorithm complexity. The design challenges that come with it are power consumption at about 1 V operating voltage, multiple chips and chip area less than 10 mm2, and the use of mixed-signal technology.

    As can be seen in the figure below, the green part is the device provided by ON Semiconductor. Its system-in-package (SiP) simplifies the assembly process of miniature hearing aids and is suitable for all hearing aid types.

    ON Semiconductor provides pre-configured DSP systems for wireless hearing aid applications, including the Ayre SA3291 hybrid module and AYRE repeater reference design. These pre-configured DSP systems offer a variety of hybrid options and function packages to support all hearing aid product types, and are very suitable for hearing aid manufacturers who require minimal programming configuration and can be applied as required.

    Among them, ON Semiconductor's Ayre SA3291 hybrid module uses a complete hearing aid algorithm suite, a pre-configured hearing processor and NFMI high-bandwidth integrated duplex radio. The antenna is the only external component required, and it can synchronize left and right ear parameters. ON Semiconductor's Ayre repeater reference design supports stereo audio streaming, Bluetooth, volume control and program selection.

    ON Semiconductor's hearing aid digital signal processing software has several distinct features, such as wide dynamic range compression, which can gently amplify sound without making the amplified sound uncomfortable, and can be customized for individual hearing loss; feedback eliminator can eliminate part of the hearing aid output signal generated by feedback, and adaptively eliminate it through phase cancellation; adaptive direction can automatically adapt the polarity pattern and adjust it according to the location of the noise; and environmental classification is used to continuously analyze the sound environment and automatically adjust the hearing aid to maximize comfort and audibility.

    To facilitate engineers' design, ON Semiconductor also provides software development tools (online tools) to help select and configure algorithms, create customized hearing aids, model electroacoustic characteristics, test algorithms, and fine-tune. If customers develop fitting software, we can provide interface communication library files; if customers do not have fitting software, we can provide customization of fitting software. Hardware development tools include DSP programmers and development boards.

    In addition to pre-configured DSP solutions, ON Semiconductor also offers the Ezairo 5900 series of open programmable DSP systems for hearing aid applications. This DSP system offers highly customizable mixed-function configuration options, which is very suitable for hearing aid manufacturers who develop their own innovative algorithms or apply fully customized algorithms provided by third-party suppliers.