Novel directional microphone design for speech enhancement in complex environments

在英国，超过50%的60岁以上的人患有听力损失，但其中只有20%的人真正使用助听器。这种低使用率的部分原因是由于目前助听器的问题，包括声音质量差以及在嘈杂和复杂环境中的性能差。但是助听器的一个功能是“定向麦克风”，它由数字信号处理和两个（至少）独立的实际麦克风组合而成。这些可以阻挡来自使用者背部或侧面的噪音。它们帮助了用户，但也带来了严重的问题。它们增加了额外的成本、重量和功率要求。它们之间必须保持一定的距离，这严重限制了助听器的整体设计。而且，只有两个麦克风的精度是相当有限的：它们可以判断声源是在前面还是后面，但很难探测到来自下面还是上面的声音，比如大房间里的回声。尽管在助听器的声音分析方面取得了显著的进步，但实际的麦克风本身几十年来基本保持不变。在这里，我们的目标是通过使用一种新型的微型定向麦克风来解决当前定向技术的问题，这种麦克风的灵感来自于一些昆虫如何解决定位声音的问题。这种新装置保持了方向性，同时保持了类似昆虫耳朵的微型尺寸。该研究项目将采用新的昆虫灵感麦克风设计，并将其作为助听器组件进行评估。从最初的评估开始，将会有一个新的、改进的、模拟、制造、实验室测试，然后评估的迭代过程。最终的结果将是麦克风可以显著解决助听器设计中面临的问题。主要目标是创造一种助听器系统，可以减少或控制不必要的噪音，使助听器只专注于从用户面前传来的声音。这不仅包括减少来自后面的噪音，还包括上面、下面和远处的噪音，例如减少来自地板和天花板的回声造成的问题。这项研究还将研究由声音发出的距离引起的问题，例如，如何将声音从远处的响亮来源（如火车或飞机）和附近的安静声音（如人声）区分开。最后，新的麦克风将需要在助听器设备中使用新的安装方法。该项目将研究使用3D打印技术来实现这一目标。这使得研究人员可以考虑如何优化助听器外壳，使其与新麦克风配合使用时在声学上达到最佳效果，以及如何将其扩展到生产适合用户耳朵和用户听觉的个性化助听器。

In the UK, more than 50% of people over 60 suffer from hearing loss, but only 20% of them actually use hearing aids. Part of this poor take-up is due to issues with current hearing aids, including poor sound quality and poor performance in noisy and complex environments. But one feature of hearing aids that does help people is a "directional microphone", made-up from a combination of digital signal processing and two (at least) separate actual microphones. These can reject noises from the back or the side of the user. They help the user but come with severe problems. They add extra cost, weight, and power requirements. They have to be a certain distance apart, severely constricting the design of the hearing aid as a whole. And, with just two microphones accuracy is quite limited: they can tell whether a sound source is in front or behind, but struggle to detect sounds from below or above, such as echoes in a large room. Despite remarkable advances in sound analysis in hearing aids, the actual microphone itself has remained essentially unchanged for decades. Here, we aim to solve the problems of current directional technology by instead using a new type of miniature directional microphone, inspired by how some insects tackle the problem of locating sounds. This new device retains its directionality while keeping the miniature dimensions similar to an insect ear. The research project will take the new insect-inspired microphone design and evaluate it as a component for hearing aids. From this initial evaluation, there will be an iterative process of new, improved, designs being simulated, fabricated, lab tested, and then evaluated. The end result will be microphones that can significantly solve the problems faced in hearing aid design.The primary objective is to create a hearing aid system that can reduce or control unwanted noises, focusing the hearing aid on only the sound arriving from in front of the user. This includes reducing noises not only from behind, but above, below and distant, so for example reducing the problems caused by echoes from floors and ceilings. The research will also look at problems caused by the distance from which a sound emanates, for example how to separate a sound from a loud source far away, like a train or plane, from a quiet sound from nearby, like a human voice. Finally, the new microphones will require new mounting methods in hearing aid devices. The project will investigate using 3D printing techniques to achieve this. This allows the research to consider how to optimise the hearing aid housing so that it works best acoustically in conjunction with the new microphone, and how it might be possible to extend that to produce hearing aids that are personalised for both the user's ear and their user's sense of hearing.