Scientific and Technical Aerospace Reports Volume 38 July 28, 2000

20000064925 Institute for Human Factors TNO, Soesterberg, Netherlands
Application of Digital Signal Processing in Active Hearing Protectors Final Report Toepassing van Digitale Signaalverwerking
in Actieve Gehoorbeschermers
Verhave, J. A., Institute for Human Factors TNO, Netherlands; Steeneken, H. J. M., Institute for Human Factors TNO, Netherlands;
Jan. 14, 2000; 26p; In Dutch; Original contains color illustrations
Contract(s)/Grant(s): A97/CO/340; TNO Proj. 786.4
Report No.(s): TD-2000-0104; TM-00-A001; Copyright; Avail: Issuing Activity
A prototype of a digital ANR (Active Noise Reduction) earmuff was developed. Application of digital signal processing
allows for a dynamic adaptation to user and environment variability’s. In comparison to analogue ANR systems an improved
sound attenuation and a more stable system is obtained. Also the speech intelligibility of the integrated intercom is improved and
the option of monitoring the sound level under the earmuff is offered. The final goal is the realization of a system that will offer
adequate hearing protection and increased intelligibility mainly, also for personnel with hearing impairment.
Author
Signal Processing; Hearing; Fabrication; Analogs; Protectors
20000064926 Defence Science and Technology Organisation, Information Technology Div., Salisbury, Australia
An Approach for Identifying and Characterizing Problems in the Iterative Development of C31 Capability
Kingston, Gina, Defence Science and Technology Organisation, Australia; Henderson, Derek, Defence Science and Technology
Organisation, Australia; Vernik, Rudi, Defence Science and Technology Organisation, Australia; November 1999; 44p; In English
Report No.(s): DSTO-TN-0238; AR-011-148; Copyright; Avail: Issuing Activity
This report presents a research approach that has been used to determine the key problems faced by the Australian Defence
Organization (ADO) in the iterative development of C3I capability. Repeated application of the approach, combined with knowledge
of strategic and’technological changes, could be used to assess process improvement activities. The approach uses interviews
of stakeholders in the Iterative Capability Development (ICD) process to gather information about the perceived problems. As
well as documenting the approach used in a study of the key problems with the ICD process, this report illustrates the application
of study design principles, such as methods for minimising potential biases in an interview-based study.
Author
Iterative Solution; Design Analysis; Optimization
20000065625 NASA Ames Research Center, Moffett Field, CA USA
Multichannel Spatial Auditory Display for Speed Communications
Begault, Durand R., NASA Ames Research Center, USA; Erbe, Tom, NASA Ames Research Center, USA; Journal of the Audio
Engineering Society; 1994; Volume 42, pp. 819-826; In English; Copyright; Avail: Issuing Activity; Abstract Only
A spatial auditory display for multiple speech communications was developed at NASA/Ames Research Center. Input is spatialized
by the use of simplifiedhead-related transfer functions, adapted for FIR filtering on Motorola 56001 digital signal processors.
Hardware and firmware design implementations are overviewed for the initial prototype developed for NASA-Kennedy
Space Center. An adaptive staircase method was used to determine intelligibility levels of four-letter call signs used by launch
personnel at NASA against diotic speech babble. Spatial positions at 30 degree azimuth increments were evaluated. The results
from eight subjects showed a maximum intelligibility improvement of about 6-7 dB when the signal was spatialized to 60 or 90
degree azimuth positions.
Author
Multichannel Communication; Radio Transmitters; Multipath Transmission; Sound Transmission; Voice Communication; Radio
Communication
20000066585 Army Research Lab., Human Research and Engineering Directorate, Aberdeen Proving Ground, MD USA
Image Steganography for Hidden Communication Final Report, Jan 1997-May 1999
Marvel, Lisa M.; Apr. 2000; 91p; In English
Report No.(s): AD-A377277; ARL-TR-2200; No Copyright; Avail: CASI; A05, Hardcopy; A01, Microfiche
Modern steganographic methods, which conceal the existence of communication, are needed to exploit contemporary modes
of information exchange. Measures of performance for these methods are essential to compare specific algorithms and determine
appropriate uses. This report develops a methodology for steganographic data hiding. The methodology encompasses derivation
of a general theory of steganographic communication, including theoretical capacity hounds, and design of an actual data-hiding
technique that used digital imagery as a cover. The technique promotes maximization of payload, allows error-free recovery of
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