Publications
Corpora for the evaluation of speaker recognition systems
March 15, 1999
Conference Paper
Published in:
ICASSP 1999, Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Processing, 15-19 March 1999.
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Summary
Using standard speech corpora for development and evaluation has proven to be very valuable in promoting progress in speech and speaker recognition research. In this paper, we present an overview of current publicly available corpora intended for speaker recognition research and evaluation. We outline the corpora's salient features with respect to their suitability for conducting speaker recognition experiments and evaluations. Links to these corpora, and to new corpora, will appear on the web http://www.apl.jhu.edu/Classes/Notes/Campbell/SpkrRec/. We hope to increase the awareness and use of these standard corpora and corresponding evaluation procedures throughout the speaker recognition community.
Summary
Using standard speech corpora for development and evaluation has proven to be very valuable in promoting progress in speech and speaker recognition research. In this paper, we present an overview of current publicly available corpora intended for speaker recognition research and evaluation. We outline the corpora's salient features with respect...
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Implications of glottal source for speaker and dialect identification
March 15, 1999
Conference Paper
Published in:
Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Processing, ICASSP, Vol. II, 15-19 March 1999, pp. 813-816.
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In this paper we explore the importance of speaker specific information carried in the glottal source. We time align utterances of two speakers speaking the same sentence from the TIMIT database of American English. We then extract the glottal flow derivative from each speaker and interchange them. Through time alignment and this glottal flow transformation, we can make a speaker of a northern dialect sound more like his southern counterpart. We also time align the utterances of two speakers of Spanish dialects speaking the same sentence and then perform the glottal waveform transformation. Through these processes a Peruvian speaker is made to sound more Cuban-like. From these experiments we conclude that significant speaker and dialect specific information, such as noise, breathiness or aspiration, and vocalization, is carried in the glottal signal.
Summary
In this paper we explore the importance of speaker specific information carried in the glottal source. We time align utterances of two speakers speaking the same sentence from the TIMIT database of American English. We then extract the glottal flow derivative from each speaker and interchange them. Through time alignment...
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'Perfect reconstruction' time-scaling filterbanks
March 15, 1999
Conference Paper
Published in:
Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Processing, ICASSP, Vol. III, 15-19 March 1999, pp. 945-948.
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A filterbank-based method of time-scale modification is analyzed for elemental signals including clicks, sines, and AM-FM sines. It is shown that with the use of some basic properties of linear systems, as well as FM-to-AM filter transduction, "perfect reconstruction" time-scaling filterbanks can be constructed for these elemental signal classes under certain conditions on the filterbank. Conditions for perfect reconstruction time-scaling are shown analytically for the uniform filterbank case, while empirically for the nonuniform constant-Q (gammatone) case. Extension of perfect reconstruction to multi-component signals is shown to require both filterbank and signal-dependent conditions and indicates the need for a more complete theory of "perfect reconstruction" time-scaling filterbanks.
Summary
A filterbank-based method of time-scale modification is analyzed for elemental signals including clicks, sines, and AM-FM sines. It is shown that with the use of some basic properties of linear systems, as well as FM-to-AM filter transduction, "perfect reconstruction" time-scaling filterbanks can be constructed for these elemental signal classes under...
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A 9PAC system and application programmer's guide
February 16, 1999
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-267
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The ASR-9 Processor Augmentation Card (9PAC) is a custom processing card that provides the ASR-9 system with increased beacon and radar processing performance. This paper describes the system and application software that executes on the prototype board, with an emphasis on the interaction between software modules. The application software on the 9PAC determines the position of radar and beacon target reports, replacing software that previously ran on the ASR-9 Array Signal Processor (ASP). The software is organized as a set of cooperating tasks executing under the control of a real-time operating system, PAC/OS, which provides all the services typical of an embedded kernel such as interrupt handling, pre-emptive multitasking, queues, signals, semaphores, mailboxes, and memory management. The deployment of 9PAC will occur in two phases. The Phase I application replaces only the beacon target detector (BTD) and radar/beacon target merge (MRG) functions of the ASP. The Phase I application consists of two executable programs since Phase I uses only two of the C44 processors on the 9PAC. One program, the housekeeping processor, is responsible for all I/O functions and performs the radar/beacon merge operation. The second progam, the beacon processor, is dedicated to processing the raw beacon replies and generating beacon targets which are then returned to the first processor for the merge operation. The Phase II application consists of three executable programs, one for each of the C44 processors on the 9PAC and performs much of the Phase I functionality and adds primary radar processing. The intent of this paper is to provide the 9PAC software support personnel with sufficient information to implement future enhancements without unintentionally compromising some aspect of the overall system.
Summary
The ASR-9 Processor Augmentation Card (9PAC) is a custom processing card that provides the ASR-9 system with increased beacon and radar processing performance. This paper describes the system and application software that executes on the prototype board, with an emphasis on the interaction between software modules. The application software on...
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Evaluating intrusion detection systems without attacking your friends: The 1998 DARPA intrusion detection evaluation
February 9, 1999
Conference Paper
Published in:
Third Conf. and Workshop on Intrusion Detection and Response, 9-13 February 1999.
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Summary
Intrusion detection systems monitor the use of computers and the network over which they communicate, searching for unauthorized use, anomalous behavior, and attempts to deny users, machines or portions of the network access to services. Potential users of such systems need information that is rarely found in marketing literature, including how well a given system finds intruders and how much work is required to use and maintain that system in a fully functioning network with significant daily traffic. Researchers and developers can specify which prototypical attacks can be found by their systems, but without access to the normal traffic generated by day-to-day work, they can not describe how well their systems detect real attacks while passing background traffic and avoiding false alarms. This information is critical: every declared intrusion requires time to review, regardless of whether it is a correct detection for which a real intrusion occurred, or whether it is merely a false alarm. To meet the needs of researchers, developers and ultimately system administrators we have developed the first objective, repeatable, and realistic measurement of intrusion detection system performance. Network traffic on an Air Force base was measured, characterized and subsequently simulated on an isolated network on which a few computers were used to simulate thousands of different Unix systems and hundreds of different users during periods of normal network traffic. Simulated attackers mapped the network, issued denial of service attacks, illegally gained access to systems, and obtained super-user privileges. Attack types ranged from old, well-known attacks, to new, stealthy attacks. Seven weeks of training data and two weeks of testing data were generated, filling more than 30 CD-ROMs. Methods and results from the 1998 DARPA intrusion detection evaluation will be highlighted, and preliminary plans for the 1999 evaluation will be presented.
Summary
Intrusion detection systems monitor the use of computers and the network over which they communicate, searching for unauthorized use, anomalous behavior, and attempts to deny users, machines or portions of the network access to services. Potential users of such systems need information that is rarely found in marketing literature, including...
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A case study of mid-level turbulence outside regions of active convection
January 10, 1999
Conference Paper
Published in:
8th Conf. on Aviation, Range, and Aerospace Meteorology (ARAM), 10-15 January 1999.
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Summary
Historically, the principal focus of research on clear-air turbulence of concern to aircraft has been on jet stream and mountain (orographic) induced turbulence. Relatively little research has focused on the turbulence hazard outside of, but in the vicinity of, convective storms, known as Convective Induced Turbulence (CIN). In this paper, we present our analysis requested by the National Transportation Safety Board (NTSB) of the meteorological conditions leading to severe turbulence and near loss of flight control of a commercial passenger jet and find that they fall into the CIN category. On 12 May 1997, at approximately 1929 UT, an American Airlines Airbus A300 en route from Boston, MA to Miami, FL encountered severe turbulence off the coast of West Palm Beach, FL. Near the time of the incident the crew had been directed to hold at 16,000 ft because of weather and traffic near Miami International. While approaching the holding position, the aircraft experienced severe turbulence and dropped over 3000 vertical feet in 30 seconds. A detailed postevent analysis by the NTSB failed to find any causal evidence for the turbulence and no single sensor, data set, or pilot report examined by the NTSB provided justification for the magnitude of the event. Our independent analysis of the incident was conducted primarily using recorded Miami WSR-88D base data. The analysis revealed a small-scale vertical shear zone may have emanated from a thunderstorm upstream of the Airbus. Animated cross-sectional images also suggested that a rotor may have propagated with the mean wind and intersected the flight path at the time the severe turbulence was reported. This paper will focus on meteorological conditions that led to the upset and provide evidence for several possible causes of the turbulence.
Summary
Historically, the principal focus of research on clear-air turbulence of concern to aircraft has been on jet stream and mountain (orographic) induced turbulence. Relatively little research has focused on the turbulence hazard outside of, but in the vicinity of, convective storms, known as Convective Induced Turbulence (CIN). In this paper...
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The thunderstorm penetration/deviation decision in the terminal area
January 10, 1999
Conference Paper
Published in:
8th Conf. on Aviation, Range and Aerospace Meteorology, ARAM, 10-15 January 1999.
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During thunderstorm periods, terminal air traffic planners make a number of key decisions. They decide when to close and re-open arrival fixes, departure fixes, and runways; they anticipate and execute changes in runway configuration; they negotiate routing and flow rate decisions with Air Route Traffic Control Center (ART CC) traffic managers; and they set the airport acceptance rate. In making each of these decisions, the traffic planner looks at a weather radar display and makes an educated guess at answering the two following questions: - What will the weather be like in the airspace and time period in question? - Will the pilots be able and willing to fly through that airspace during that time? The same two questions will be important for advanced terminal automation systems. One key element of air traffic automation systems such as the Center-TRACON Automation System (CTAS) is the calculation of candidate trajectories for each aircraft for the time period of automation control. To make this calculation, the automation software must know which routes will be usable during the control period. The first of the two fundamental questions is being addressed by the convective weather Product Development Team (PDT) of the FAA's Aviation Weather Research program. (Wolfson, 1997; Wolfson, 1999; Hallowell, 1999; Forman, 1999; Evans, 1997) The second fundamental question is the subject of the work reported here. The state of the art answer to the second question is a widely quoted air traffic control rule-of-thumb which says that pilots generally do not penetrate precipitation that is NWS VIP level 3 (i.e. 41 dBZ) or higher. That is not to say that air traffic controllers always vector aircraft around level 3+ cells but rather that they begin to anticipate pilot requests for deviations when the weather approaches level 3. A suite of new weather sensors have become available that provide much more comprehensive information on convective weather features than was available in the past. Additionally, flight-related data such as preceding pilot behavior and whether a flight is running late are easier to obtain than in the past. In this study we develop an objective quantitative assessment of which weather and flight-related variables best explain pilot deviation decision-making.
Summary
During thunderstorm periods, terminal air traffic planners make a number of key decisions. They decide when to close and re-open arrival fixes, departure fixes, and runways; they anticipate and execute changes in runway configuration; they negotiate routing and flow rate decisions with Air Route Traffic Control Center (ART CC) traffic...
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Achieving higher integrity in NEXRAD products through multi-sensor integration
January 10, 1999
Conference Paper
Published in:
8th Conf. on Aviation, Range, and Aerospace Meteorology (ARAM), 10-15 January 1999.
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The initial operational concept for the NEXRAD focused on support for the operational forecaster based on longstanding practice in use of weather radars by the National Weather Service (NWS) and Air Force as well as difficulties in developing reliable, fully automated phenomena detection algorithms [Crum, 1998]. By contrast, achieving high integrity in the narrow band products provided by NEXRAD to external users has received much less attention in the NEXRAD product development process thus far. However, other government weather information systems [especially the FAA's Integrated Terminal Weather System (ITWS) and the Weather and Radar Processor (WARP)] and non-meteorologist external users of the NEXRAD products through the NEXRAD Information Distribution System (NIDS) vendors need very high integrity NEXRAD products. In the NWS context, the direct utilization of NEXRAD products into numerical weather prediction models will also create much more stringent requirements for integrity of the NEXRAD base data. Achieving very high integrity through automated analysis of only the data from a single NEXRAD is very difficult. In this paper, we consider the use of a much wider range of contextual information to create high integrity external user products. For instance, with the NEXRAD Open RPG and connectivity to AWIPS and ITWS, a system architecture will exist that will facilitate the implementation of NEXRAD product quality control algorithms that utilize information from other sensors. In the following sections, we present some examples of how information from various other sources might be used to improve the quality of the data from a NEXRAD. We first show an example of how data from adjacent NEXRADs can be used to help edit out the anomalous propagation (AP) ground clutter which currently is corrupting a number of the NEXRAD reflectivity products intended for air traffic controller use. In cases where the NEXRAD is near a major metropolitan area, data from the FAA's TDWR can be used to improve the integrity of the NEXRAD reflectivity products used for hydrology. Similarly, gridded wind fields estimated from multiple Doppler analyses, aircraft reports, and numerical models can be used to help address difficult challenges in Doppler ambiguity resolution for a single NEXRAD radar. The paper concludes with suggestions for near term demonstration and evaluation of multi sensor approaches to achieving high integrity in the NEXRAD products.
Summary
The initial operational concept for the NEXRAD focused on support for the operational forecaster based on longstanding practice in use of weather radars by the National Weather Service (NWS) and Air Force as well as difficulties in developing reliable, fully automated phenomena detection algorithms [Crum, 1998]. By contrast, achieving high...
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A refinement of thunderstorm climatology for the terminal radar control airspace
January 10, 1999
Conference Paper
Published in:
8th Conf. on Aviation, Range and Aerospace Meteorology, ARAM, 10-15 January 1999.
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Convective storms pose a significant threat to aviation safety, and often result in substantial fl ight delays for the commercial aviation industry. The overall impact of these storms is typically based on thunderstorm climatologies and are often one of the factors used in decisions by the US government regarding the operational benefits and allocation of its weather surveillance resources. These climatologies are based on the average number of days that a thunderstorm is observed at a particular airport. Due to the nature of the criteria used to identify a thunderstorm, the climatological statistics often do not accurately represent the number of thunderstorms that impact an airport's operations. The present study utilizes data from the Dallas Ft. Worth International Airport (DFW) and the Orlando International Airport (MCO) to identify deficiencies in the climatological data as it applies to aviation applications. A spatially representative climatology is presented as a more accurate climatology for use in evaluating the impact of convection on an airport's operations. This type of climatological estimate of thunderstorm frequency significantly increases the estimated number of thunderstorms impacting an airport and their associated costs.
Summary
Convective storms pose a significant threat to aviation safety, and often result in substantial fl ight delays for the commercial aviation industry. The overall impact of these storms is typically based on thunderstorm climatologies and are often one of the factors used in decisions by the US government regarding the...
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Addressing the weather delay problems of the New York City airports with the Integrated Terminal Weather System
January 10, 1999
Conference Paper
Published in:
8th Conf. on Aviation, Range, and Aerospace Meteorology, 10-15 1999.
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The three major New York City (NYC) air carrier airports (Kennedy, LaGuardia, Newark) currently experience high delays due to adverse terminal weather, both in an absolute sense and relative to other major airport complexes. Significantly expanding the NYC airports (e.g., by adding new runways) to reduce delays is not feasible. One alternative is to provide aviation weather decision support systems to air traffic, airline, and airport operations personnel to help them operate more safely and effectively with the existing runway/taxiway complexes. Under an innovative partnership between the Port Authority of New York and New Jersey and the Federal Aviation Administration (FAA), Massachusetts Institute of Technology, Lincoln Laboratory has installed and is currently operating a functional prototype Integrated Terminal Weather System (ITWS) to conduct research on improving the safety and efficiency of operations at the NYC airports during adverse weather. The New York terminal area provides a stringent test of the ITWS ability to safely reduce delays due to both the meteorology and the operational usage challenges not found at the earlier ITWS test locations of Orlando, Memphis, and Dallas. In this paper, we describe key features of the New York terminal environment and the ITWS prototype, the initial experience in addressing the meteorological and operational usage challenges of the New York terminal area, and describe plans for the coming years.
Summary
The three major New York City (NYC) air carrier airports (Kennedy, LaGuardia, Newark) currently experience high delays due to adverse terminal weather, both in an absolute sense and relative to other major airport complexes. Significantly expanding the NYC airports (e.g., by adding new runways) to reduce delays is not feasible...
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