11Anti-phase method + frequency shifting methodAnti-phase Sound having the opposite waveform to the sound re-entering the microphone from the hearing aid is used to cancel out the amplified sound.methodFrequency shifting Sound having frequencies over approximately 1,000 Hz is always shifted 20 Hz before outputting it to prevent the amplification of the sound at the same frequency.methodFrequencyFrequency[Rionet Precia II] (2015)Arriving in 2015, two years after the introduction of the Rionet Precia, the Rio-net Precia II was an upgraded model of its popular predecessor. The most nota-ble upgrade was SSS Speech+, an enhanced version of the SSS (Sound Spectrum Shaping) function in Rionet Rosé. Unlike its predecessor, SSS Speech+ encom-passed the 250 Hz and 500 Hz bands in its target, facilitating clearer perception of all vowels in the Japanese language. Furthermore, this enhancement empha-sized the distinction between peak enhancement and dip attenuation across all bands.[Rionet series] (2017)The flagship model, launched in 2017, is powered by the new proprietary sig-nal processing unit, the Rionet Engine, achieving a remarkable 40% reduction in processing time compared to its predecessor, the Rionet Precia II. Upgrades extend to key features such as feedback cancellation, reverberation suppression, speech enhancement, and noise suppression, all aimed at delivering a clear-er and more natural hearing experience. Additionally, this model introduces an automatic mode switching function, allowing the hearing aid to seamlessly adapt to the current sound environment by selecting the most appropriate dig-ital mode.The feature of AFBCαThe problem of sharp whistling noise created by hearing aids is known as feedback. It occurs when sounds amplified and output from the receiver are picked up by the microphone and amplified repeatedly. Since the re-ceiver and microphone in a hearing aid unit are located close to each oth-er, this can happen quite often at higher volumes. The AFBCα feedback canceller simultaneously employs the anti-phase method and the frequen-cy shifting method to suppress feedback. Adopted by numerous manufac-turers, the anti-phase method can reduce feedback by cancelling wave-forms of the original signal with waveforms having precisely the opposite phase. The frequency shifting method reduces feedback by shifting the fre-quency band at the point at which feedback occurs. The two methods are used in combination for quick and effective feedback suppression. AFBCα feedback canceller has proven to be particularly effective in cases involving open fitting, where the muffling or reverberation of sound are suppressed by opening large vents (ventilation holes) or in cases in which the gain is high, or the mouth is in motion, or when the user is making phone calls. It effectively reduces burdens on the user.Yamada, who is responsible for the electrical design of hearing aids and supports product development from the hardware side, adds, “Even from a hardware perspective, there’s no doubt that the Precia series set the foundations for the development of later models of digital hearing aids. Var-ious models were developed using the Precia platform. The creation of a stable platform at such a high level of perfection significantly increased development efficiency.”One of the most prominent features of Rionet Precia is how it attempts to strengthen the feedback cancellation func-tion. Feedback is a loud and unpleasant sound like sharp whis-tling that prevents users from continuing to wear the hearing aid. It’s an issue that must be addressed in the development process. The upgraded feedback cancellation function in Ri-onet Precia prevents this unpleasant sound by combining the anti-phase method and the frequency shifting method. It’s has been named the AFBCα. The feedback cancellation margin, which represents the control value for preventing feedback, was approximately 15 dB for Rionet Rosé II. This was improved to approximately 25 dB for Rionet Precia, which expanded the user scope to include people with higher hearing threshold levels (i.e., people who have more difficulty in hearing) and thereby expanded the range of products offered by Rion. This head-on approach to one of the key issues associated with hearing aids led to the development of the new feature that allowed Rionet Precia to be even more versatile than before.The Rionet Precia II, released in 2015, was an upgraded version of Rionet Precia equipped with an innovative new technology called SSS Speech+, an upgraded version of the SSS first introduced in Rionet Rosé. It offers a revolutionary feature for facilitating the perception of speech in the Japa-nese language.“There are five vowels in the Japanese language. A fre-quency analysis on these five vowels reveals that the five formants (resonant frequencies) from F1 to F5 appear at dif-ferent frequencies for each vowel. The differences in formant frequencies enable us to distinguish them. The SSS processing band did not cover frequencies that could become formants at low frequencies, making it difficult for users to perceive some vowels. With SSS Speech+, expanding the frequency range that can be processed to the 250 Hz band allows Japanese vowels to be heard more clearly,” explains Yamada.SSS Speech+, developed through joint research efforts with a university hospital, demonstrated Rion’s technological development capabilities and the expertise in digital hearing aids.“The digitalization of hearing aids has made it possible for us to meet the diverse needs of our customers,” says Osawa. “Each person has a different set of criteria for how comfort-able to hear; each will have different needs depending on the situation. With digital technologies, we are able to incorporate a wider range of functions. We can offer more and more op-tions for users to choose from.” In fact, Rion’s digital hearing aids have dramatically evolved since 2015. That’s a story for the next issue.Pride in being a Japanese hearing aid manufacturer＋＝
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