Local representations and random sampling for speaker verification

In text-independent speaker verification, studies focused on compensating intra-speaker variabilities at the modeling stage through the last decade. Intra-speaker variabilities may be due to channel effects, phonetic content or the speaker himself in the form of speaking style, emotional state, health or other similar factors. Joint Factor Analysis, Total Variability Space compensation, Nuisance Attribute Projection are some of the most successful approaches for inter-session variability compensation in the literature. In this thesis, we criticize the assumptions of low dimensionality of channel space in these methods and propose to partition the acoustic space into local regions. Intra-speaker variability compensation may be done in each local space separately. Two architectures are proposed depending on whether the subsequent modeling and scoring steps will also be done locally or globally. We have also focused on a particular component of intra-speaker variability, namely within-session variability. The main source of within-session variability is the differences in the phonetic content of speech segments in a single utterance. The variabilities in phonetic content may be either due to across acoustic event variabilities or due to differences in the actual realizations of the acoustic events. We propose a method to combat these variabilities through random sampling of training utterance. The method is shown to be effective both in short and long test utterances

PLDA-based diarization of telephone conversations

This paper investigates the application of the probabilistic linear discriminant analysis (PLDA) to speaker diarization of telephone conversations. We introduce using a variational Bayes (VB) approach for inference under a PLDA model for modelling segmental i-vectors in speaker diarization. Deterministic annealing (DA) algorithm is imposed in order to avoid local optimal solutions in VB iterations. We compare our proposed system with a well-known system that applies k-means clustering on principal component analysis (PCA) coefficients of segmental i-vectors. We used summed channel telephone data from the National Institute of Standards and Technology (NIST) 2008 Speaker Recognition Evaluation (SRE) as the test set in order to evaluate the performance of the proposed system. We achieve about 20% relative improvement in Diarization Error Rate (DER) compared to the baseline system

Tübitak UEKAE - Sabancı Üniversitesi NIST SRE 2010 konuşmacı doğrulama sistemi (Tübıtak UEKAE - Sabanci University NIST SRE 2010 Speaker verification system)

NIST Speaker Recognition Evaluations (NIST SRE), played a major role in the progress of text-independent speaker verification algorithms. Tübitak UEKAE - Sabancı University jointly participated in NIST SRE 2010. In this paper, the Gaussian Mixture Model Supervector - Support Vector Machine based speaker verification system developed for NIST SRE 2010 has been presented. A recipe has been given for the training of Universal Background Model which is an essential step for system's performance. Results of the Nuisance Attribute Projection algorithm integrated to the system after evaluation to suppress the session variabilities has also been presented

Deferasirox in children with transfusion-dependent thalassemia or sickle cell anemia: A large cohort real-life experience from Turkey (REACH-THEM)

Objectives To evaluate the long-term efficacy and safety of deferasirox therapy in a large observational cohort of children with transfusion-dependent thalassemia (TDT) and sickle cell anemia (SCA) in Turkey. Methods This was a multicenter, prospective cohort study including TDT and SCA patients aged 2-18 years with iron overload (>= 100 mL/kg of pRBC or a serum ferritin [SF] level >1000 mu g/L) receiving deferasirox. Patients were followed for up to 3 years according to standard practice. Results A total of 439 patients were evaluated (415 [94.5%] TDT, 143 [32.6%] between 2 and 6 years). Serum ferritin levels consistently and significantly decreased across 3 years of deferasirox therapy from a median of 1775.5 to 1250.5 mu g/L (P = 30 mg/kg/d (n = 120, -579.6 median reduction, P = 30 mg/kg/d) may be required to achieve iron balance