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RECOG: Recognition and Exploration of Content Graphs

Published in:
Pacific Vision, 26 February - March 1, 2013.

Summary

We present RECOG (Recognition and Exploration of COntent Graphs), a system for visualizing and interacting with speaker content graphs constructed from large data sets of speech recordings. In a speaker content graph, nodes represent speech signals and edges represent speaker similarity. First, we describe a layout algorithm that optimizes content graphs for ease of navigability. We then present an interactive tool set that allows an end user to find and explore interesting occurrences in the corpus. We also present a tool set that allows a researcher to visualize the shortcomings of current content graph generation algorithms. RECOG's layout and toolsets were implemented as Gephi plugins [1].
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Summary

We present RECOG (Recognition and Exploration of COntent Graphs), a system for visualizing and interacting with speaker content graphs constructed from large data sets of speech recordings. In a speaker content graph, nodes represent speech signals and edges represent speaker similarity. First, we describe a layout algorithm that optimizes content...

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Social network analysis with content and graphs

Published in:
Lincoln Laboratory Journal, Vol. 20, No. 1, 2013, pp. 62-81.

Summary

Social network analysis has undergone a renaissance with the ubiquity and quantity of content from social media, web pages, and sensors. This content is a rich data source for constructing and analyzing social networks, but its enormity and unstructured nature also present multiple challenges. Work at Lincoln Laboratory is addressing the problems in constructing networks from unstructured data, analyzing the community structure of a network, and inferring information from networks. Graph analytics have proven to be valuable tools in solving these challenges. Through the use of these tools, Laboratory researchers have achieved promising results on real-world data. A sampling of these results are presented in this article.
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Summary

Social network analysis has undergone a renaissance with the ubiquity and quantity of content from social media, web pages, and sensors. This content is a rich data source for constructing and analyzing social networks, but its enormity and unstructured nature also present multiple challenges. Work at Lincoln Laboratory is addressing...

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Graph embedding for speaker recognition

Published in:
Chapter in Graph Embedding for Pattern Analysis, 2013, pp. 229-60.

Summary

This chapter presents applications of graph embedding to the problem of text-independent speaker recognition. Speaker recognition is a general term encompassing multiple applications. At the core is the problem of speaker comparison-given two speech recordings (utterances), produce a score which measures speaker similarity. Using speaker comparison, other applications can be implemented-speaker clustering (grouping similar speakers in a corpus), speaker verification (verifying a claim of identity), speaker identification (identifying a speaker out of a list of potential candidates), and speaker retrieval (finding matches to a query set).
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Summary

This chapter presents applications of graph embedding to the problem of text-independent speaker recognition. Speaker recognition is a general term encompassing multiple applications. At the core is the problem of speaker comparison-given two speech recordings (utterances), produce a score which measures speaker similarity. Using speaker comparison, other applications can be...

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Characterization of traffic and structure in the U.S. airport network

Summary

In this paper we seek to characterize traffic in the U.S. air transportation system, and to subsequently develop improved models of traffic demand. We model the air traffic within the U.S. national airspace system as dynamic weighted network. We employ techniques advanced by work in complex networks over the past several years in characterizing the structure and dynamics of the U.S. airport network. We show that the airport network is more dynamic over successive days than has been previously reported. The network has some properties that appear stationary over time, while others exhibit a high degree of variation. We characterize the network and its dynamics using structural measures such as degree distributions and clustering coefficients. We employ spectral analysis to show that dominant eigenvectors of the network are nearly stationary with time. We use this observation to suggest how low dimensional models of traffic demand in the airport network can be fashioned.
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Summary

In this paper we seek to characterize traffic in the U.S. air transportation system, and to subsequently develop improved models of traffic demand. We model the air traffic within the U.S. national airspace system as dynamic weighted network. We employ techniques advanced by work in complex networks over the past...

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Query-by-example using speaker content graphs

Published in:
INTERSPEECH 2012: 13th Annual Conf. of the Int. Speech Communication Assoc., 9-13 September 2012.

Summary

We describe methods for constructing and using content graphs for query-by-example speaker recognition tasks within a large speech corpus. This goal is achieved as follows: First, we describe an algorithm for constructing speaker content graphs, where nodes represent speech signals and edges represent speaker similarity. Speech signal similarity can be based on any standard vector-based speaker comparison method, and the content graph can be constructed using an efficient incremental method for streaming data. Second, we apply random walk methods to the content graph to find matching examples to an unlabeled query set of speech signals. The content-graph based method is contrasted to a more traditional approach that uses supervised training and stack detectors. Performance is compared in terms of information retrieval measures and computational complexity. The new content-graph based method is shown to provide a promising low-complexity scalable alternative to standard speaker recognition methods.
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Summary

We describe methods for constructing and using content graphs for query-by-example speaker recognition tasks within a large speech corpus. This goal is achieved as follows: First, we describe an algorithm for constructing speaker content graphs, where nodes represent speech signals and edges represent speaker similarity. Speech signal similarity can be...

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Individual and group dynamics in the reality mining corpus

Published in:
Proc. 2012 ASE/IEEE Int. Conf. on Social Computing, 3-5 September 2012, pp. 61-70.

Summary

Though significant progress has been made in recent years, traditional work in social networks has focused on static network analysis or dynamics in a large-scale sense. In this work, we explore ways in which temporal information from sociographic data can be used for the analysis and prediction of individual and group behavior in dynamic, real-world situations. Using the MIT Reality Mining corpus, we show how temporal information in highly-instrumented sociographic data can be used to gain insights otherwise unavailable from static snapshots. We show how pattern of life features extend from the individual to the group level. In particular, we show how anonymized location information can be used to infer individual identity. Additionally, we show how proximity information can be used in a multilinear clustering framework to detect interesting group behavior over time. Experimental results and discussion suggest temporal information has great potential for improving both individual and group level understanding of real-world, dense social network data.
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Summary

Though significant progress has been made in recent years, traditional work in social networks has focused on static network analysis or dynamics in a large-scale sense. In this work, we explore ways in which temporal information from sociographic data can be used for the analysis and prediction of individual and...

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A stochastic system for large network growth

Published in:
IEEE Signal Process. Lett., Vol. 19, No. 6, June 2012, pp. 356-359.

Summary

This letter proposes a new model for preferential attachment in dynamic directed networks. This model consists of a linear time-invariant system that uses past observations to predict future attachment rates, and an innovation noise process that induces growth on vertices that previously had no attachments. Analyzing a large citation network in this context, we show that the proposed model fits the data better than existing preferential attachment models. An analysis of the noise in the dataset reveals power-law degree distributions often seen in large networks, and polynomial decay with respect to age in the probability of citing yet-uncited documents.
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Summary

This letter proposes a new model for preferential attachment in dynamic directed networks. This model consists of a linear time-invariant system that uses past observations to predict future attachment rates, and an innovation noise process that induces growth on vertices that previously had no attachments. Analyzing a large citation network...

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Moments of parameter estimates for Chung-Lu random graph models

Published in:
ICASSP 2012, Proc. IEEE Int. Conf. on Acoustics, Speech, and Signal Processing, 25-30 March 2012, pp. 3961-4.

Summary

As abstract representations of relational data, graphs and networks find wide use in a variety of fields, particularly when working in non- Euclidean spaces. Yet for graphs to be truly useful in in the context of signal processing, one ultimately must have access to flexible and tractable statistical models. One model currently in use is the Chung- Lu random graph model, in which edge probabilities are expressed in terms of a given expected degree sequence. An advantage of this model is that its parameters can be obtained via a simple, standard estimator. Although this estimator is used frequently, its statistical properties have not been fully studied. In this paper, we develop a central limit theory for a simplified version of the Chung-Lu parameter estimator. We then derive approximations for moments of the general estimator using the delta method, and confirm the effectiveness of these approximations through empirical examples.
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Summary

As abstract representations of relational data, graphs and networks find wide use in a variety of fields, particularly when working in non- Euclidean spaces. Yet for graphs to be truly useful in in the context of signal processing, one ultimately must have access to flexible and tractable statistical models. One...

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Eigenspace analysis for threat detection in social networks

Published in:
Int. Conf. on Information Fusion, 5 July 2011.

Summary

The problem of detecting a small, anomalous subgraph within a large background network is important and applicable to many fields. The non-Euclidean nature of graph data, however, complicates the application of classical detection theory in this context. A recent statistical framework for anomalous subgraph detection uses spectral properties of a graph's modularity matrix to determine the presence of an anomaly. In this paper, this detection framework and the related algorithms are applied to data focused on a specific application: detection of a threat subgraph embedded in a social network. The results presented use data created to simulate threat activity among noisy interactions. The detectability of the threat subgraph and its separability from the noise is analyzed under a variety of background conditions in both static and dynamic scenarios.
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Summary

The problem of detecting a small, anomalous subgraph within a large background network is important and applicable to many fields. The non-Euclidean nature of graph data, however, complicates the application of classical detection theory in this context. A recent statistical framework for anomalous subgraph detection uses spectral properties of a...

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Graph relational features for speaker recognition and mining

Published in:
Proc. 2011 IEEE Statistical Signal Processing Workshop (SSP), 28-30 June 2011, pp. 525-528.

Summary

Recent advances in the field of speaker recognition have resulted in highly efficient speaker comparison algorithms. The advent of these algorithms allows for leveraging a background set, consisting a large numbers of unlabeled recordings, to improve recognition. In this work, a relational graph, where nodes represent utterances and links represent speaker similarity, is created from the background recordings in which the recordings of interest, train and test, are then embedded. Relational features computed from the embedding are then used to obtain a match score between the recordings of interest. We show the efficacy of these features in speaker verification and speaker mining tasks.
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Summary

Recent advances in the field of speaker recognition have resulted in highly efficient speaker comparison algorithms. The advent of these algorithms allows for leveraging a background set, consisting a large numbers of unlabeled recordings, to improve recognition. In this work, a relational graph, where nodes represent utterances and links represent...

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