Speex是一套主要针对语音的开源免费，无专利保护的应用集合，它不仅包括编解码器，还包括VAD(语音检测),DTX(不连续传输),AEC(回声消除),NS(去噪)等实用模块。(Speex is a set of open source free, patent free application set, which is mainly for voice. It not only includes codec, but also includes VAD (voice detection), DTX (discontinuous transmission), AEC (echo cancellation), NS (denoising) and other practical modules.)