Tactical communications bring new challenges to automatic speech recognition

Abstract

Automatic speaker-independent recognition of conversational speech has been making significant progress in recent years. Military communications challenge the robustness of current recognition systems. Compared to telephone conversations or news broadcasts, tactical communication has a reduced vocabulary. It consists of short utterances, limited to the task at hand, with occasional chat words. What makes recognition difficult is high levels of background noise in tactical environments (helicopters, tanks) and the degradation of the signal by military microphones, including noise canceling microphones. Of perhaps more importance, people alter their speech to overcome these degradations and the loss of intelligibility from communicating over vocoders. The DARPA-sponsored spine program is exploring these issues using speech from pairs of participants performing a collaborative task while communicating between separate sound booths. Each person sits in an accurately reproduced military background noise environment and uses the type of microphone and ear protection that would normally be found in that environment. The communication is conducted through vocoders. This presentation will review results from the spine evaluations of state-of-the-art speech recognition systems and from analyses of the transcripts in an attempt to understand how environmental factors and speaking changes affect recognizer performance. [Work supported by DARPA.]