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Speaker recognition using G.729 speech codec parameters

June 5, 2000
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Conference Paper
Author:
Thomas F. Quatieri
…
Published in:
Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Processing, ICASSP, Vol. II, 5-9 June 2000, pp. 1089-1092.
Topic:
speaker recognition
R&D area:
R&D group:

Summary

Experiments in Gaussian-mixture-model speaker recognition from mel-filter bank energies (MFBs) of the G.729 codec all-pole spectral envelope, showed significant performance loss relative to the standard mel-cepstral coefficients of G.729 synthesized (coded) speech. In this paper, we investigate two approaches to recover speaker recognition performance from G.729 parameters, rather than deriving cepstra from MFBs of an all-pole spectrum. Specifically, the G.729 LSFs are converted to "direct" cepstral coefficients for which there exists a one-to-one correspondence with the LSFs. The G.729 residual is also considered; in particular, appending G.729 pitch as a single parameter to the direct cepstral coefficients gives further performance gain. The second nonparametric approach uses the original MFB paradigm, but adds harmonic striations to the G.729 all-pole spectral envelope. Although obtaining considerable performance gains with these methods, we have yet to match the performance of G.729 synthesized speech, motivating the need for representing additional fine structure of the G.729 residual.
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Summary

Experiments in Gaussian-mixture-model speaker recognition from mel-filter bank energies (MFBs) of the G.729 codec all-pole spectral envelope, showed significant performance loss relative to the standard mel-cepstral coefficients of G.729 synthesized (coded) speech. In this paper, we investigate two approaches to recover speaker recognition performance from G.729 parameters, rather than deriving...

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Speaker recognition using G.729 speech codec parameters

Weather radar development and application programs

June 1, 2000
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Journal Article
Author:
James E. Evans
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Published in:
Lincoln Laboratory Journal, Vol. 12, No. 2, 2000, pp. 367-382.
Topic:
aviation weather
R&D area:
R&D group:

Summary

Weather phenomena such as microburst wind shear and severe thunderstorms are major concerns to the aviation industry. A number of significant airplane accidents have resulted from wind-shear encounters during takeoff and landing, and thunderstorms are a major contributor to airplane delay. Providing fully automated and timely warnings of these phenomena by radar is challenging because it requires rapid and accurate analysis of the three-dimensional storm structure in the presence of intense ground-clutter returns. For the last two decades, Lincoln Laboratory has been tackling this challenge by applying advanced radar signal- and image-processing techniques to weather radar data. The resulting technology is being deployed in radar-based weather information systems at major airports throughout the United States. We first discuss the salient meteorological factors that contribute to the formation of microburst wind shear, then we provide some general background on the use of pulse-Doppler radar for weather detection. We describe two specific Lincoln Laboratory programs that have generated deployed systems: the Terminal Doppler Weather Radar (TDWR) and the ASR-9 Weather Systems Processor (WSP). The article concludes with a discussion of future detection strategies that emphasizes the fusion of weather radar data by the Integrated Terminal Weather System (ITWS).
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Summary

Weather phenomena such as microburst wind shear and severe thunderstorms are major concerns to the aviation industry. A number of significant airplane accidents have resulted from wind-shear encounters during takeoff and landing, and thunderstorms are a major contributor to airplane delay. Providing fully automated and timely warnings of these phenomena...

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Weather radar development and application programs

The NIST Speaker Recognition Evaluation - overview, methodology, systems, results, perspective

June 1, 2000
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Journal Article
Author:
George R. Doddington
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Published in:
Speech Commun., Vol. 31, Nos. 2-3, June 2000, pp. 225-254.
Topic:
speaker recognition
R&D area:
R&D group:

Summary

This paper, based on three presentations made in 1998 at the RLA2C Workshop in Avignon, discusses the evaluation of speaker recognition systems from several perspectives. A general discussion of the speaker recognition task and the challenges and issues involved in its evaluation is offered. The NIST evaluations in this area and specifically the 1998 evaluation, its objectives, protocols and test data, are described. The algorithms used by the systems that were developed for this evaluation are summarized, compared and contrasted. Overall performance results of this evaluation are presented by means of detection error trade-off (DET) curves. These show the performance trade-off of missed detections and false alarms for each system and the effects on performance of training condition, test segment duration, the speakers' sex and the match or mismatch of training and test handsets. Several factors that were found to have an impact on performance, including pitch frequency, handset type and noise, are discussed and DET curves showing their effects are presented. The paper concludes with some perspective on the history of this technology and where it may be going.
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Summary

This paper, based on three presentations made in 1998 at the RLA2C Workshop in Avignon, discusses the evaluation of speaker recognition systems from several perspectives. A general discussion of the speaker recognition task and the challenges and issues involved in its evaluation is offered. The NIST evaluations in this area...

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The NIST Speaker Recognition Evaluation - overview, methodology, systems, results, perspective

The design and validation of the ITWS synthetic sensor data generator

April 12, 2000
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Project Report
Author:
Margita L. Pawlak
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Published in:
MIT Lincoln Laboratory Report ATC-289
Topic:
modeling
R&D area:
R&D group:

Summary

The Integrated Terminal Weather System (ITWS) is an aviation safety and air traffic management decision support system that acquires data from various FAA and NWS sensors and generates a number of products for dissemination to FAA facilities managing air traffic in the terminal area. The development and demonstrations of ITWS have been conducted over a multi-year period at several major airports (Memphis, TN, Orlando, FL, Dallas, TX, and New York, NY). Although there are many meteorological events observed at these four airports, the experimental test data sets obtained will not fully suffice for ITWS qualification testing because of limitations in the severity of the weather events and because of the sensor configurations available at these locations. This report describes the design and validation of the Synthetic Data Generator (SDG), which is a tool to provide a production ITWS system with meteorologically consistent scenarios and full ITWS sensor configurations that will create maximal computational loads that can be expected when the system is deployed. Also, the SDG will be a tool for ongoing ITWS maintenance and support. As such, the SDG will complement the extensive experimental data sets collected at the four ITWS demonstration sites. The SDG is designed to specify parameters for a collection of meteorological models describing the various weather phenomena, their motion, appearance, and growth/decay. The software creates several three-dimensional (3D) grids of reflectivity and velocity at each time-step. Finally, the SDG generates sensor (i.e., TDWR, NEXRAD, ASR-9) data by applying the model for each specific sensor's measurements to the 3D grids. The validation of the meteorological model and the sensor model data have been accomplished using a display tool and by assessing results numerically.
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Summary

The Integrated Terminal Weather System (ITWS) is an aviation safety and air traffic management decision support system that acquires data from various FAA and NWS sensors and generates a number of products for dissemination to FAA facilities managing air traffic in the terminal area. The development and demonstrations of ITWS...

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The design and validation of the ITWS synthetic sensor data generator

Spectral beam combining of a broad-stripe diode laser array in an external cavity

March 15, 2000
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Journal Article
Author:
Vincenzo Daneu
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Published in:
Opt. Lett., Vol. 25, No. 6, 15 March 2000, pp. 405-407.
Topic:
lasers
R&D area:
R&D group:

Summary

The outputs from an 11-element, linear diode laser array with broad stripes have been beam combined into a single beam with a beam quality of ~20X diffraction limited in the plane of the junction. This beam combining was achieved by use of a common external cavity containing a grating, which simultaneously forces each array element to operate at a different, but controlled, wavelength and forces the beams from all the elements to overlap and propagate in the same direction. The power in the combined beam was 50% of the output from the bare laser array.
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Summary

The outputs from an 11-element, linear diode laser array with broad stripes have been beam combined into a single beam with a beam quality of ~20X diffraction limited in the plane of the junction. This beam combining was achieved by use of a common external cavity containing a grating, which...

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Spectral beam combining of a broad-stripe diode laser array in an external cavity

An enhanced bandwidth design technique for electromagnetically coupled microstrip antennas

February 1, 2000
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Journal Article
Author:
Sean M. Duffy
Published in:
IEEE Trans. Antennas Propag., Vol. 48, No. 2, February 2000, pp. 161-164.
Topic:
antennas
R&D area:
R&D group:

Summary

This paper describes a method of enhancing the bandwidth of two different electromagnetically coupled microstrip antennas by utilization of a tuning stub. An approximate theory and equations are developed to demonstrate the potential bandwidth improvement and required stub impedance characteristics. A novel dual-stub design is presented that achieves better characteristics than a conventional quarter wavelength open-end stub. As examples, the bandwidth (VSWR < 2) of a conventional proximity-coupled microstrip antenna is increased from 4.8 to 8.4% and the bandwidth of a stacked aperture-coupled microstrip antenna is increased from 27.5 to 34.5% using this technique.
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Summary

This paper describes a method of enhancing the bandwidth of two different electromagnetically coupled microstrip antennas by utilization of a tuning stub. An approximate theory and equations are developed to demonstrate the potential bandwidth improvement and required stub impedance characteristics. A novel dual-stub design is presented that achieves better characteristics...

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An enhanced bandwidth design technique for electromagnetically coupled microstrip antennas

The development of phased-array radar technology

January 1, 2000
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Journal Article
Author:
Alan J. Fenn
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Published in:
Lincoln Laboratory Journal, Vol. 12, No. 2, 2000, pp. 321-340.
Topic:
integrated circuit
R&D area:
R&D group:

Summary

Lincoln Laboratory has been involved in the development of phased-array radar technology since the late 1950s. Radar research activities have included theoretical analysis, application studies, hardware design, device fabrication, and system testing. Early phased-array research was centered on improving the national capability in phased-array radars. The Laboratory has developed several test-bed phased arrays, which have been used to demonstrate and evaluate components, beamforming techniques, calibration, and testing methodologies. The Laboratory has also contributed significantly in the area of phased-array antenna radiating elements, phase-shifter technology, solid-state transmit-and-receive modules, and monolithic microwave integrated circuit (MMIC) technology. A number of developmental phased-array radar systems have resulted from this research, as discussed in other articles in this issue. A wide variety of processing techniques and system components have also been developed. This article provides an overview of more than forty years of this phased-array radar research activity.
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Summary

Lincoln Laboratory has been involved in the development of phased-array radar technology since the late 1950s. Radar research activities have included theoretical analysis, application studies, hardware design, device fabrication, and system testing. Early phased-array research was centered on improving the national capability in phased-array radars. The Laboratory has developed several...

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The development of phased-array radar technology

Information Survivability for Mobile Wireless Systems

January 1, 2000
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Journal Article
Author:
Thomas M. Parks
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Published in:
Lincoln Laboratory Journal, Vol. 12, No. 1, pp. 65-80.
Topic:
communications
R&D area:
R&D group:

Summary

Mobile wireless networks are more vulnerable to cyber attack and more difficult to defend than conventional wired networks. In discussing security and survivability issues in mobile wireless networks, we focus here on group communication, as applied to multimedia conferencing. The need to conserve resources in wireless networks encourages the use of multicast protocols for group communication, which introduces additional security concerns. We point out the need for rate-adaptation techniques to simultaneously support multiple receivers that each experience different network conditions. The security properties associated with a number of approaches to rate adaptation are compared. We also identify several security issues for reliable group communication, providing examples of denial-of-service attacks and describing appropriate security measures to guard against such attacks. We examine the costs of these security measures in terms of network efficiency and computational overhead. Finally, we introduce a survivability approach called dynamically deployed protocols, in which the effects of an information attack are mitigated by dynamically switching to a new protocol to evade the attack. We suggest that this dynamic protocol deployment can be achieved effectively by transmission of in-line mobile code.
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Summary

Mobile wireless networks are more vulnerable to cyber attack and more difficult to defend than conventional wired networks. In discussing security and survivability issues in mobile wireless networks, we focus here on group communication, as applied to multimedia conferencing. The need to conserve resources in wireless networks encourages the use...

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Information Survivability for Mobile Wireless Systems

Approaches to speaker detection and tracking in conversational speech

January 1, 2000
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Journal Article
Author:
Robert B. Dunn
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Published in:
Digit. Signal Process., Vol. 10, No. 1, January/April/July, 2000, pp. 93-112. (Fifth Annual NIST Speaker Recognition Workshop, 3-4 June 1999.)
Topic:
speaker recognition
R&D area:
R&D group:

Summary

Two approaches to detecting and tracking speakers in multispeaker audio are described. Both approaches use an adapted Gaussian mixture model, universal background model (GMM-UBM) speaker detection system as the core speaker recognition engine. In one approach, the individual log-likelihood ratio scores, which are produced on a frame-by-frame basis by the GMM-UBM system, are used to first partition the speech file into speaker homogenous regions and then to create scores for these regions. We refer to this approach as internal segmentation. Another approach uses an external segmentation algorithm, based on blind clustering, to partition the speech file into speaker homogenous regions. The adapted GMM-UBM system then scores each of these regions as in the single-speaker recognition case. We show that the external segmentation system outperforms the internal segmentation system for both detection and tracking. In addition, we show how different components of the detection and tracking algorithms contribute to the overall system performance.
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Summary

Two approaches to detecting and tracking speakers in multispeaker audio are described. Both approaches use an adapted Gaussian mixture model, universal background model (GMM-UBM) speaker detection system as the core speaker recognition engine. In one approach, the individual log-likelihood ratio scores, which are produced on a frame-by-frame basis by the...

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Approaches to speaker detection and tracking in conversational speech

Speaker verification using adapted Gaussian mixture models

January 1, 2000
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Journal Article
Author:
Douglas A. Reynolds
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Published in:
Digit. Signal Process., Vol. 10, No. 1-3, January/April/July, 2000, pp. 19-41. (Fifth Annual NIST Speaker Recognition Workshop, 3-4 June 1999.)
Topic:
speaker recognition
R&D area:
R&D group:

Summary

In this paper we describe the major elements of MIT Lincoln Laboratory's Gaussian mixture model (GMM)-based speaker verification system used successfully in several NIST Speaker Recognition Evaluations (SREs). The system is built around the likelihood ratio test for verification, using simple but effective GMMs for likelihood functions, a universal background model (UBM) for alternative speaker representation, and a form of Bayesian adaptation to derive speaker models from the UBM. The development and use of a handset detector and score normalization to greatly improve verification performance is also described and discussed. Finally, representative performance benchmarks and system behavior experiments on NIST SRE corpora are presented.
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Summary

In this paper we describe the major elements of MIT Lincoln Laboratory's Gaussian mixture model (GMM)-based speaker verification system used successfully in several NIST Speaker Recognition Evaluations (SREs). The system is built around the likelihood ratio test for verification, using simple but effective GMMs for likelihood functions, a universal background...

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Speaker verification using adapted Gaussian mixture models
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