Stephanie S. Everett

Natural Language in Four Spatial Interfaces

We describe our experiences building spoken language interfaces to four demonstration applications all involving 2- or 3-D spatial displays or gestural interactions: an air combat command and control simulation, an immersive VR tactical scenario viewer, a map-based air strike simulation tool with cartographic database, and a speech/gesture controller for mobile robots.

Improvement of the LPC analysis

The narrowband linear predictive coder (LPC) is becoming widely used in both civilian and military applications. Yet, in spite of the many improvements made over the years, it is still not universally acceptable to general users. Therefore we present improvements to three aspects of the LPC analysis to increase the quality and intelligibility of the narrowband LPC. They are: (1) frequency spreading of voiceless fricative sound spectra, (2) adaptive analysis-window placement at onsets, and (3) suppression of intraframe pitch interference.

Automatic speaker recognition using vocoded speech

Automatic speaker recognition (ASR) offers potential benefit for numerous applications, including identification of users of communication channels such as the telephone and channels using processed or vocoded speech. Currently the listener must subjectively determine whether the person on the other end of the line is who he or she claims to be. However, when the speech is processed, recognition of voices can be very difficult for human listeners. A series of tests was conducted to evaluate the feasibility of automatic speaker recognition with processed or vocoded speech. The analog outputs of six different voice processors were used as input to a real-time ASR system. Recognition accuracy results for the processed speech were 70% to 95% using a 2500 Hz bandwidth input filter, and 75% to 95% using a 4000 Hz input filter. These results indicate that ASR using vocoded speech is definitely feasible, though further research is needed to determine which speech parameters are best suited for use with each voice processor.

Using speech and audio in the interface (abstract)

TOPIC A workshop entitled The Future of Speech and Audio in the Interface [1] was held at CHI ’94 with the goal of further defining the emerging area of sound in user interfaces and applications, and exploring applications, research areas, and interaction techniques that use audio in the interface. The focus of the workshop was on the “CHI perspective” of using speech and sound to exploit the audio channel for the user’s benefit. This SIG is designed as a follow-on to that workshop; the focus of the workshop will provide the focus for this session as well.

Word synthesis based on line spectrum pairs

The author described the initial investigation of a synthetic speech system based on line spectrum pair (LSP) analysis of the speech signal. The synthesizer contains a library of stored LSP speech segments extracted from natural speech. These segments are modified as necessary by a small set of context-sensitive rules and then concatenated to generate high-quality natural-sounding speech. Tests of a preliminary system produced MRT and DRT scores of 87.3 and 79.7, respectively. The LSP vocabulary synthesizer is limited to utterances of a single syllable, but future research will expand its capabilities to allow implementation of a full text-to-speech system.<<ETX>>

A Spoken Language Interface to a Virtual Reality System (Video)

Stephanie S. Everett, Kenneth Wauchope Navy Ctr . for Appl ied Resea rch in AI Naval Resea rch L a b o r a t o r y W a s h i n g t o n , DC 20375, USA e v e r e t t I w a u c h o p e