Development and Construct of Speech Privacy Protection System Using Masking Effect

最近，在开放空间中实现言论隐私的重要性得到了强调。在本研究中，开发了一种利用掩蔽噪声实现语音隐私的系统。我们采用了无意义的稳定噪声来掩盖各种功率谱的演讲，闭式耳机/喉式麦克风在高噪声环境下也能清晰地传递语音。通过对各种指标的评估，选择最有效的指标来达到令人满意的语音隐私水平。从结果中，选择频谱距离作为评价语音隐私的最佳指标。每个人的语音频谱是不同的，因此使用与个体语音频谱相对应的掩蔽噪声可以有效地减少烦恼。从这个观点出发，构造了一种装置来产生与声音具有相同频谱形式的噪声。通过心理实验验证了所构建装置的有效性。上述系统存在一些问题：偶尔会辐射过多的掩蔽噪声，由于喉部麦克风的频率特性不平坦，语音通信质量略差。为了考虑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来提高可听性和听力分数的有效性，进行了心理实验。心理学实验对开发的紧凑型/便携型/轻型等系统进行了评价。结果证实了所开发系统的有效性。

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.