An electronic communication system is set forth that includes the transmission of a narrowband speech signal corresponding to a narrowband version of speech utterances of a speaker as well as the transmission of speaker-dependent data. The speaker-dependent data may be used to correlate narrowband versions...http://www.google.com.hk/patents/US7693714?utm_source=gb-gplus-share專利 US7693714 - System for generating a wideband signal from a narrowband signal using transmitted speaker-dependent data
