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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

A survey of the state-of-the-art and focused research in range systems, task 1

This final report presents the latest research activity in voice compression. We have designed a non-real time simulation system that is implemented around the IBM-PC where the IBM-PC is used as a speech work station for data acquisition and analysis of voice samples. A real-time implementation is also proposed. This real-time Voice Compression Board (VCB) is built around the Texas Instruments TMS-3220. The voice compression algorithm investigated here was described in an earlier report titled, Low Cost Voice Compression for Mobile Digital Radios, by the author. We will assume the reader is familiar with the voice compression algorithm discussed in this report. The VCB compresses speech waveforms at data rates ranging from 4.8 K bps to 16 K bps. This board interfaces to the IBM-PC 8-bit bus, and plugs into a single expansion slot on the mother board.

Omura, J. K.↗
NASA NTRS1984

Artificial intelligence, expert systems, computer vision, and natural language processing

An overview of artificial intelligence (AI), its core ingredients, and its applications is presented. The knowledge representation, logic, problem solving approaches, languages, and computers pertaining to AI are examined, and the state of the art in AI is reviewed. The use of AI in expert systems, computer vision, natural language processing, speech recognition and understanding, speech synthesis, problem solving, and planning is examined. Basic AI topics, including automation, search-oriented problem solving, knowledge representation, and computational logic, are discussed.

Gevarter, W. B.↗
NASA NTRS1987

The effects of display-control I/O, compatibility, and integrality on dual-task performance and subjective workload

The utility of speech technology was evaluated in terms of three dual task principles: resource competition between the time shared tasks, stimulus central processing response compatibility, and task integrality. Empirical support for these principles was reviewed. Two studies investigating the interactive effects of the three principles were described. Objective performance and subjective workload ratings for both single and dual tasks were examined. It was found that the single task measures were not necessarily good predictors for the dual task measures. It was shown that all three principles played an important role in determining an optimal task configuration. This was reflected in both the performance measures and the subjective measures. Therefore, consideration of all three principles is required to insure proper use of speech technology in a complex environment.

Tsang, Pamela S.↗
NASA NTRS1988

Space-Station-Interior Noise-Analysis Program

Intelligibility of speech evaluated for specified acoustical environments. Program makes systematic prediction of noise and vibration environment of craft defined by user and evaluates relative acceptability of predicted environment for effective communication by speech. Written in MicroSoft FORTRAN Version 3.3.

Stusnick, Eric↗
NASA NTRS1986

Integrated voice and visual systems research topics

A series of studies was performed to investigate factors of helicopter speech and visual system design and measure the effects of these factors on human performance, both for pilots and non-pilots. The findings and conclusions of these studies were applied by the U.S. Army to the design of the Army's next generation threat warning system for helicopters and to the linguistic functional requirements for a joint Army/NASA flightworthy, experimental speech generation and recognition system.

Williams, Douglas H.↗
NASA NTRS1988

Voice-stress measure of mental workload

In a planned experiment, male subjects between the age of 18 and 50 will be required to produce speech while performing various tasks. Analysis of the speech produced should reveal which aspects of voice prosody are associated with increased workloads. Preliminary results with two female subjects suggest a possible trend for voice frequency and amplitude to be higher and the variance of the voice frequency to be lower in the high workload condition.

Alpert, Murray↗
NASA NTRS1988

ACSB: A minimum performance assessment

Amplitude companded sideband (ACSB) is a new modulation technique which uses a much smaller channel width than does conventional frequency modulation (FM). Among the requirements of a mobile communications system is adequate speech intelligibility. This paper explores this aspect of minimum required performance. First, the basic principles of ACSB are described, with emphasis on those features that affect speech quality. Second, the appropriate performance measures for ACSB are reviewed. Third, a subjective voice quality scoring method is used to determine the values of the performance measures that equate to the minimum level of intelligibility. It is assumed that the intelligibility of an FM system operating at 12 dB SINAD represents that minimum. It was determined that ACSB operating at 12 dB SINAD with an audio-to-pilot ratio of 10 dB provides approximately the same intelligibility as FM operating at 12 dB SINAD.

Jones, Lloyd Thomas↗
NASA NTRS1987

Checklist interruption and resumption: A linguistic study

This study forms part of a project investigating the relationships among the formal structure of aviation procedures, the ways in which the crew members are taught to execute them, and the ways in which thet are actually performed in flight. Specifically, this report examines the interactions between the performance of checklists and interruptions, considering both interruptions by radio communications and by other crew members. The data consists of 14 crews' performance of a full mission simulation of a higher ratio of checklist speech acts to all speech acts within the span of the performance of the checklist. Further, it is not number of interruptions but length of interruptions which is associated with crew performance quality. Use of explicit holds is also associated with crew performance.

Linde, Charlotte↗
NASA NTRS1987

Communications indices of crew coordination

Verbal exchanges occuring during task execution during full mission two-person simulator flights are used to study the effect of the interactive communication process on crew coordination and performance. The ratio of initiator to response speech is calculated and speech variations are recorded. The results of this study are compared with the findings of Ginnett's (1986) study of leaders. It is shown that low-error crews adopt a standard form of communicating, allowing for the ability to predict one another's behavior, facilitating the coordination process. The higher performance of crews that have flown together before is believed to be due to the increased amount of time for establishing a conventional means of communication.

Kanki, Barbara G.↗
NASA NTRS1989

Communication variations and aircrew performance

Crew-related communication variations and their effects on performance are examined. The communication analysis involves evaluating the performance of 18 pilots to a high-fidelity full-mission simulation. Initiating speech consists of four categories: commands, questions, observations, and dysfluencies. Response speech is coded as: reply, acknowledgements, and zero response. A standard form of communication has been adopted which should aid in the coordination process and enhance crew performance.

Kanki, Barbara G.↗
NASA NTRS1990

Remote voice training: A case study on space shuttle applications, appendix C

The Tile Automation System includes applications of automation and robotics technology to all aspects of the Shuttle tile processing and inspection system. An integrated set of rapid prototyping testbeds was developed which include speech recognition and synthesis, laser imaging systems, distributed Ada programming environments, distributed relational data base architectures, distributed computer network architectures, multi-media workbenches, and human factors considerations. Remote voice training in the Tile Automation System is discussed. The user is prompted over a headset by synthesized speech for the training sequences. The voice recognition units and the voice output units are remote from the user and are connected by Ethernet to the main computer system. A supervisory channel is used to monitor the training sequences. Discussions include the training approaches as well as the human factors problems and solutions for this system utilizing remote training techniques.

Mollakarimi, Cindy↗
NASA NTRS1991

Communication variations and aircrew performance

The relationship between communication variations and aircrew performance (high-error vs low-error performances) was investigated by analyzing the coded verbal transcripts derived from the videotape records of 18 two-person air transport crews who participated in a high-fidelity, full-mission flight simulation. The flight scenario included a task which involved abnormal operations and required the coordinated efforts of all crew members. It was found that the best-performing crews were characterized by nearly identical patterns of communication, whereas the midrange and poorer performing crews showed a great deal of heterogeneity in their speech patterns. Although some specific speech sequences can be interpreted as being more or less facilitative to the crew-coordination process, predictability appears to be the key ingredient for enhancing crew performance. Crews communicating in highly standard (hence predictable) ways were better able to coordinate their task, whereas crews characterized by multiple, nonstandard communication profiles were less effective in their performance.

Kanki, Barbara G.↗
NASA NTRS1991

Communication variations related to leader personality

While communication and captain personality type have been separately shown to relate to overall crew performance, this study attempts to establish a link between communication and personality among 12 crews whose captains represent three pre-selected personality profiles (IE+, I-, Ec-). Results from analyzing transcribed speech from one leg of a full-mission simulation study, so far indicate several discriminating patterns involving ratios of total initiating speech (captain to crew members); in particular commands, questions and observations.

Kanki, Barbara G.↗
NASA NTRS1994

Frequency-Shift Hearing Aid

Proposed hearing aid maps spectrum of speech into band of lower frequencies at which ear remains sensitive. By redirecting normal speech frequencies into frequency band from 100 to 1,500 Hz, hearing aid allows people to understand normal conversation, including telephone calls. Principle operation of hearing aid adapted to other uses such as, clearing up noisy telephone or radio communication. In addition, loud-speakers more easily understood in presence of high background noise.

Weinstein, Leonard M.↗
NASA NTRS1993

Noise levels and their effects on Shuttle crewmembers' performance: Operational concerns

When excessive, noise can result in sleep interference, fatigue, interference with verbal communication, and hearing damage. Shuttle crewmembers are exposed to noise throughout their mission. The contribution of noise to decrements in crew performance over these extended exposure durations was the focus of this study. On the STS-40/SLS-1, mission noise levels were evaluated through the use of a sound level meter and a crew questionnaire. Crewmembers noted that sleep, concentration, and relaxation were negatively impacted by high noise levels. Speech Interference Levels (SIL's), calculated from the sound level measurements, suggested that crewmembers were required to raise their voice in order to be heard. No difficulty detecting caution and warning alarms was noted. The higher than desirable noise levels in Spacelab were attributed to flight specific payloads for which acoustic waivers were granted. It is recommended that current noise levels be reduced in Spacelab and the Orbiter Middeck especially as longer missions are planned for the buildup of Space Station Freedom. Levels of NC 50 are recommended in areas where speech communication is required and NC 40 in sleep areas. These levels are in accordance with the NASA Man-Systems Integration Standards. Measurements proposed for subsequent orbiter missions are discussed.

Koros, Anton S.↗
NASA NTRS1993

Call sign intelligibility improvement using a spatial auditory display

A spatial auditory display was used to convolve speech stimuli, consisting of 130 different call signs used in the communications protocol of NASA's John F. Kennedy Space Center, to different virtual auditory positions. An adaptive staircase method was used to determine intelligibility levels of the signal against diotic speech babble, with spatial positions at 30 deg azimuth increments. Non-individualized, minimum-phase approximations of head-related transfer functions were used. The results showed a maximal intelligibility improvement of about 6 dB when the signal was spatialized to 60 deg or 90 deg azimuth positions.

Begault, Durand R.↗
NASA NTRS1994

Automatic translation among spoken languages

The Machine Aided Voice Translation (MAVT) system was developed in response to the shortage of experienced military field interrogators with both foreign language proficiency and interrogation skills. Combining speech recognition, machine translation, and speech generation technologies, the MAVT accepts an interrogator's spoken English question and translates it into spoken Spanish. The spoken Spanish response of the potential informant can then be translated into spoken English. Potential military and civilian applications for automatic spoken language translation technology are discussed in this paper.

Walter, Sharon M.↗