Chienchung Chang

A robust speech recognition system embedded in CDMA cellular phone chipsets

PureVoice™ VR is a speech recognition system characterized by noise robustness performance, small footprint, and limited computing requirement. The system was embedded into Qualcomms Code Division Multiple Access (CDMA) Mobile Station Modem (MSM) chipsets. The PureVoice™ VR engine enabled many manufactures of CDMA cellular phones to add highly accurate voice-activated dialing features to their handsets and hands-free car kits without significant increase in hardware cost. Users of these cellular phones could make calls by simply speaking names or phone numbers. The current embedded system has the capacity to recognize 100 speaker-dependent (SD) nametags and user defined commands, or 30 speaker-independent (SI) digits and commands in realtime. It also works in a hybrid mode, in which an input utterance can be either SD namtags or SI commands. PureVoice™ VR has successfully supported the voice-activated dialing function for millions of CDMA handsets sold in the world market.

Interactive speech recognition apparatus and method with conditioned voice prompts

An improved system for an interactive voice recognition system (400) includes a voice prompt generator (401) for generating voice prompt in a first frequency band (501). A speech detector (406) detects presence of speech energy in a second frequency band (502). The first and second frequency bands (501, 502) are essentially conjugate frequency bands. A voice data generator (412) generates voice data based on an output of the voice prompt generator (401) and audible speech of a voice response generator (402). A control signal (422) controls the voice prompt generator (401) based on whether the speech detector (406) detects presence of speech energy in the second frequency band (502). A back end (405) of the interactive voice recognition system (400) is configured to operate on an extracted front end voice feature based on whether the speech detector (406) detects presence of speech energy in the second frequency band (502).