Unifying Cosine and PLDA Back-ends for Speaker Verification (original) (raw)
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Improving PLDA Speaker Verification Performance using Domain Mismatch Compensation Techniques
Computer Speech & Language, 2018
The performance of state-of-the-art i-vector speaker verification systems relies on a large amount of training data for probabilistic linear discriminant analysis (PLDA) modeling. During the evaluation, it is also crucial that the target condition data is matched well with the development data used for PLDA training. However, in many practical scenarios, these systems have to be developed, and trained, using data that is often outside the domain of the intended application, since the collection of a significant amount of in-domain data is often difficult. Experimental studies have found that PLDA speaker verification performance degrades significantly due to this development/evaluation mismatch. This paper introduces a domain-invariant linear discriminant analysis (DI-LDA) technique for out-domain PLDA speaker verification that compensates domain mismatch in the LDA subspace. We also propose a domain-invariant probabilistic linear discriminant analysis (DI PLDA) technique for domain mismatch modeling in the PLDA subspace, using only a small amount of in-domain data. In addition, we propose the sequential and score-level combination of DI-LDA, and DI-PLDA to further improve out-domain speaker verification performance. Experimental results show the proposed domain mismatch compensation techniques yield at least 27% and 14.5% improvement in equal error rate (EER) over a pooled PLDA system for telephone-telephone and interview-interview conditions, respectively. Finally, we show that the improvement over the baseline pooled system can be attained even when significantly reducing the number of in-domain speakers, down to 30 in most of the evaluation conditions.
UTD-CRSS SYSTEMS FOR 2018 NIST SPEAKER RECOGNITION EVALUATION
In this study, we present systems submitted by the Center for Robust Speech Systems (CRSS) from UTDallas to NIST SRE 2018 (SRE18). Three alternative front-end speaker embedding frameworks are investigated, that includes: (i) i-vector, (ii) x-vector, (iii) and a modified triplet speaker embedding system (t-vector). Similar to the previous SRE, language mismatch between training and en-rollment/test data, the so-called domain mismatch, remains as a major challenge in this evaluation. In addition, SRE18 also introduces a small portion of audio from an unstructured video corpus in which speaker detection/diarization is supposedly needed to be effectively integrated into speaker recognition for system robustness. In our system development, we focused on: (i) building novel deep neural network based speaker discriminative embedding systems as utterance level feature representations, (ii) exploring alternative dimension reduction methods, back-end classifiers, score normalization techniques which can incorporate unlabeled in-domain data for domain adaptation, (iii) finding an improved data set configurations for the speaker embedding network, LDA/PLDA, and score calibration training (v) and finally, investigating effective score calibration and fusion strategies. The final resulting systems are shown to be both complementary and effective in achieving overall improved speaker recognition performance.
Dataset-Invariant Covariance Normalization for Out-domain PLDA Speaker Verification
16th Annual Conference of the International Speech Communication Association, Interspeech 2015, 2015
In this paper we introduce a novel domain-invariant covariance normalization (DICN) technique to relocate both in-domain and out-domain i-vectors into a third dataset-invariant space, providing an improvement for out-domain PLDA speaker verification with a very small number of unlabelled in-domain adaptation i-vectors. By capturing the dataset variance from a global mean using both development out-domain i-vectors and limited unlabelled in-domain i-vectors, we could obtain domain-invariant representations of PLDA training data. The DICN-compensated out-domain PLDA system is shown to perform as well as in-domain PLDA training with as few as 500 unlabelled in-domain i-vectors for NIST-2010 SRE and 2000 unlabelled in-domain i-vectors for NIST-2008 SRE, and considerable relative improvement over both out-domain and in-domain PLDA development if more are available.
PLDA based Speaker Verification with Weighted LDA Techniques
The Speaker and Language Recognition Workshop (Odyssey 2012), 2012
This paper investigates the use of the dimensionality-reduction techniques weighted linear discriminant analysis (WLDA), and weighted median fisher discriminant analysis (WMFD), before probabilistic linear discriminant analysis (PLDA) modeling for the purpose of improving speaker verification performance in the presence of high inter-session variability. Recently it was shown that WLDA techniques can provide improvement over traditional linear discriminant analysis (LDA) for channel compensation in i-vector based speaker verification systems. We show in this paper that the speaker discriminative information that is available in the distance between pair of speakers clustered in the development i-vector space can also be exploited in heavy-tailed PLDA modeling by using the weighted dis-criminant approaches prior to PLDA modeling. Based upon the results presented within this paper using the NIST 2008 Speaker Recognition Evaluation dataset, we believe that WLDA and WMFD projections before PLDA modeling can provide an improved approach when compared to uncompensated PLDA modeling for i-vector based speaker verification systems.
Digital Signal Processing, 2014
The availability of multiple utterances (and hence, i-vectors) for speaker enrollment brings up several alternatives for their utilization with probabilistic linear discriminant analysis (PLDA). This paper provides an overview of their effective utilization, from a practical viewpoint. We derive expressions for the evaluation of the likelihood ratio for the multi-enrollment case, with details on the computation of the required matrix inversions and determinants. The performance of five different scoring methods, and the effect of i-vector length normalization is compared experimentally. We conclude that length normalization is a useful technique for all but one of the scoring methods considered, and averaging i-vectors is the most effective out of the methods compared. We also study the application of multicondition training on the PLDA model. Our experiments indicate that multicondition training is more effective in estimating PLDA hyperparameters than it is for likelihood computation. Finally, we look at the effect of the configuration of the enrollment data on PLDA scoring, studying the properties of conditional dependence and number-of-enrollment-utterances per target speaker. Our experiments indicate that these properties affect the performance of the PLDA model.
DICN for Out-domain PLDA Speaker Verification
In this paper we introduce a novel domain-invariant covariance normalization (DICN) technique to relocate both in-domain and out-domain i-vectors into a third dataset-invariant space, pro- viding an improvement for out-domain PLDA speaker verifica- tion with a very small number of unlabelled in-domain adapta- tion i-vectors. By capturing the dataset variance from a global mean using both development out-domain i-vectors and lim- ited unlabelled in-domain i-vectors, we could obtain domain- invariant representations of PLDA training data. The DICN- compensated out-domain PLDA system is shown to perform as well as in-domain PLDA training with as few as 500 unlabelled in-domain i-vectors for NIST-2010 SRE and 2000 unlabelled in-domain i-vectors for NIST-2008 SRE, and considerable rel- ative improvement over both out-domain and in-domain PLDA development if more are available.
PLDA Modeling in the Fishervoice Subspace for Speaker Verification
We have previously developed a Fishervoice framework that maps the JFA-mean supervectors into a compressed discriminant subspace using nonparametric Fishers discriminant analysis. It was shown that performing cosine distance scoring (CDS) on these Fishervoice projected vectors (denoted as f-vectors) can outperform the classical joint factor analysis. Unlike the ivector approach in which the channel variability is suppressed in the classification stage, in the Fishervoice framework, channel variability is suppressed when the f-vectors are constructed. In this paper, we investigate whether channel variability can be further suppressed by performing Gaussian probabilistic discriminant analysis (PLDA) in the classification stage. We also use random subspace sampling to enrich the speaker discriminative information in the f-vectors. Experiments on NIST SRE10 show that PLDA can boost the performance of Fishervoice in speaker verification significantly by a relative decrease of 14.4% in minDCF (from 0.526 to 0.450).
Speaker-Aware Linear Discriminant Analysis in Speaker Verification
Interspeech 2020
Linear discriminant analysis (LDA) is an effective and widely used discriminative technique for speaker verification. However, it only utilizes the information on global structure to perform classification. Some variants of LDA, such as local pairwise LDA (LPLDA), are proposed to preserve more information on the local structure in the linear projection matrix. However, considering that the local structure may vary a lot in different regions, summing up related components to construct a single projection matrix may not be sufficient. In this paper, we present a speaker-aware strategy focusing on preserving distinct information on local structure in a set of linear discriminant projection matrices, and allocating them to different local regions for dimension reduction and classification. Experiments on NIST SRE2010 and NIST SRE2016 show that the speaker-aware strategy can boost the performance of both LDA and LPLDA backends in i-vector systems and x-vector systems.
Discriminative multi-domain PLDA for speaker verification
2016 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), 2016
Domain mismatch occurs when data from application-specific target domain is related to, but cannot be viewed as iid samples from the source domain used for training speaker models. Another problem occurs when several training datasets are available but their domains differ. In this case training on simply merged subsets can lead to suboptimal performance. Existing approaches to cope with these problems employ generative modeling and consist of several separate stages such as training and adaptation. In this work we explore a discriminative approach which naturally incorporates both scenarios in a principled way. To this end, we develop a method that can learn across multiple domains by extending discriminative probabilistic linear discriminant analysis (PLDA) according to multi-task learning paradigm. Our results on the recent JHU Domain Adaptation Challenge (DAC) dataset demonstrate that the proposed multi-task PLDA decreases equal error rate (EER) of the PLDA without domain compensation by more than 35% relative and performs comparable to another competitive domain compensation technique.
Discriminatively trained Probabilistic Linear Discriminant Analysis for speaker verification
2011 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), 2011
Recently, i-vector extraction and Probabilistic Linear Discriminant Analysis (PLDA) have proven to provide state-of-the-art speaker verification performance. In this paper, the speaker verification score for a pair of i-vectors representing a trial is computed with a functional form derived from the successful PLDA generative model. In our case, however, parameters of this function are estimated based on a discriminative training criterion. We propose to use the objective function to directly address the task in speaker verification: discrimination between same-speaker and different-speaker trials. Compared with a baseline which uses a generatively trained PLDA model, discriminative training provides up to 40% relative improvement on the NIST SRE 2010 evaluation task.