Development and Construct of Speech Privacy Protection System Using Masking Effect

最近，在开放空间中实现语音隐私的重要性已经被强调。在这项研究中，开发了一种使用掩蔽噪声实现语音隐私的系统。采用无意义的稳态噪声掩蔽不同功率谱的语音，采用封闭式耳机/喉式麦克风在高噪声环境下也能提供清晰的语音。1.通过对各种指标的综合评价，选择出最有效的语音隐私保护指标。结果表明，频谱距离是评价语音隐私性的最佳指标。2.语音的频谱因个体而异，使用与个体语音频谱相对应的掩蔽噪声可以有效地减少干扰。从这个观点出发，构造了一种装置，以产生与语音具有相同频谱形式的噪声。3.上述系统存在的问题是：偶尔会辐射出太多的掩蔽噪声，并且由于喉部麦克风的频率特性不平坦，语音通信质量稍差。通过心理学实验，考察了考虑背景噪声的掩蔽噪声对降低噪声和烦恼的有效性，以及通过校正喉部麦克风的频率特性对提高可听度和听力分数的有效性。4.对所开发的紧凑型/便携型/轻便型系统进行了心理学实验评估。结果证实了所开发的系统的实用性。

Recently the importance of achieving speech privacy in open spaces has been emphasized. In this study, a system for achieving speech privacy using a masking noise was developed. We adopted a meaningless steady noise to mask speeches that has various power spectra, and closed headphones/throat microphones to deliver clear speech even in high noise environments.1.The most effective index for achieving a satisfactory level of speech privacy is selected by evaluating various indices. From the results, spectral distance was selected as the best index for evaluating speech privacy.2.The spectrum of speech differs between individuals, so using masking noise corresponding to individual voice spectra was effective in minimizing annoyance. From this viewpoint, a device was constructed to generate noise with the same spectrum form as a voice. Psychological experiments were conducted to consider the validity of the device constructed.3.The above system had some problems : occasionally it radiated too much masking noise, and voice communication quality was slightly poor because the frequency characteristics of the throat microphones were not flat. To consider the effectiveness of reducing the noisiness and annoyance by using masking noise which takes background noise into account, and the effectiveness of improving audibility and listening score by correcting frequency characteristic of throat microphones, psychological experiments were conducted.4.Psychological experiments were conducted to evaluate the developed compact/portable/light-wait system. The results confirmed the usefulness of the developed system.