Baidu's Deep-Learning System Rivals People at Speech Recognition

China's leading Internet-search company, Baidu, has developed a voice system that can recognize English and Mandarin speech better than people, in some cases. The new system, called Deep Speech 2, is especially significant in how it relies entirely on machine learning for translation. Whereas older voice-recognition systems include many handcrafted components to aid audio processing and transcription, the Baidu system learned to recognize words from scratch, simply by listening to thousands of hours of transcribed audio. The technology relies on a powerful technique known as deep learning, which involves training a very large multilayered virtual network of neurons to recognize patterns in vast quantities of data. The Baidu app for smartphones lets users search by voice, and also includes a voice-controlled personal assistant called Duer (see "Baidu's Duer Joins the Personal Assistant Party").