Signal processing & audio processors

Abstract

Signal processing algorithms are the hidden components in the audio processor that converts the received acoustic signal into electrical impulses while maintaining as much relevant information as possible. Signal processing algorithms should be smart enough to mimic the functionality of external, middle and the inner-ear to provide the cochlear implant (CI) user with a hearing experience as natural as possible. Modern sound processing strategies are based on the continuous interleaved sampling (CIS) strategy proposed by B. Wilson in 1991, which provided envelope information over several intracochlear electrodes. The CIS strategy brought significant gains in speech perception. Translational research activities of MED-EL resulted in further improvements in speech understanding in noisy environments as well as enjoyment of music by not only coding CIS-based envelope information, but by also representing temporal fine structure information in the stimulation patterns of the apical channels. Further developments include “complete cochlear coverage” made possible by deep insertion of the intracochlear electrode, elaborate front end processing, anatomy based fitting (ABF), triphasic pulse stimulation instrumental in the suppression of facial nerve stimulation, and bimodal delay compensation allowing unilateral CI users to experience hearing with hearing aids on the contralateral ear. The large number of hardware developments might be exemplified by the RONDO, the world's first single unit audio processor in 2013. This article covers the milestones of translational research around the signal processing and audio processor topic that took place in association with MED-EL.

Graphical Abstract

Chinese abstract

信号处理算法是音频处理器中的隐密组件。它将接收到的声音信号转换为电脉冲, 而在转换过程中不会丢失任何信息。信号处理算法应高明到可以模仿外耳、中耳和内耳的功能, 从而为CI植入者提供自然的听觉体验。信号处理方面的突破发生在1991年, 当时美国的Wilson教授提出了连续交错采样（CIS）策略。该策略使得电极通道的非同时刺激成为可能。精细结构处理（FSP）策略是对CIS策略的改进, 它在MED-EL的信号处理策略中起着关键作用。该信号处理策略通过以相同的频率并与低频中的声频同步施加电脉冲来模仿自然。本章涵盖了MED-EL的转换研究活动, 评估了FSP的功效、前端处理功能以及音频处理器的开发。根据解剖特征的安装（ABF）是一个新概念, 即根据个人的频率图和电极插入深度进行安装。三相脉冲刺激是另一个有助于抑制面神经刺激的新概念。双峰延迟补偿这一概念允许单侧CI使用者利用对侧耳朵的助听器来体验相配的听力。

Keywords:

• Continuous interleaved sampling
• fine structure processing
• single unit processor
• anatomy-based fitting
• triphasic pulse stimulation
• bimodal delay compensation

Acknowledgments

The authors would gratefully like to acknowledge the key contributors to the development of the subject matter. Their contributions are outlined in this article. The authors further acknowledge Peter Nopp and Reinhold Schatzer from MED-EL for their valuable input and comments during several rounds of review meetings that contributed to the final version of this article.

Disclosure statement

This article is sponsored by MED-EL and has not undergone the regular peer-review process of Acta Oto-Laryngologica. Both the authors are affiliated with MED-EL.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.