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Unsupervised Evaluation of Speaker Recognition System
Odehnal, Ondřej ; Plchot, Oldřich (referee) ; Matějka, Pavel (advisor)
Tato práce je vystavěna nad moderním systémem pro rozpoznávání mluvčího (SID) založeného na x-vektorech. Cílem bakalářské práce je navrhnout a experimentálně vyhodnotit techniky pro evaluaci SID systému za použití audio nahrávek bez anotace tj. bez znalosti mluvčího. Pro tento účel je z každé nahrávky bez anotace vytvořen embedding. Ty se poté používají pro shlukování nahrávek a následné vytvoření pseudo-anotací. Na těchto anotacích se SID systém evaluuje pomocí equal error rate (EER) metriky. Za účelem vytvoření pseudo-anotací byly navrženy tyto shlukovací algoritmy učení bez učitele: K-means, Gaussian mixture models (GMM) a aglomerativní shlukování. Po testování vyšel jakožto nejlepší experimentální postup K-means se Silhouette metrikou, která používá kosinovou podobnost jako míru vzdálenosti. Nejlepší metoda dosáhla 5,72 % EER s referenčním EER = 5,15 %, které bylo spočítané se znalostí anotace na části datasetu SITW dev-core-core. Podobné výsledky byly získány na části datasetu SITW eval-core-core s odhadnutým EER = 5,86 % a referenčním 5,08 %. Rozdíl mezi hodnotami tvoří 0,57 % pro eval-core-core a 0, 78% pro dev-core-core. Další testy na NIST SRE16 a VoxCeleb1 datasetech byly provedeny za účelem ověření správnosti navrženého postupu. Obecně se dá říct, že navržený testovací postup měl chybu přibližně 1 %, což je poměrně dobrý výsledek pro algoritmus učení bez učitele.
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The Evolution of Optimum Currency Area Index: Post-crisis Perspective
Kadlecová, Pavlína ; Horváth, Roman (advisor) ; Geršl, Adam (referee)
This paper estimates the determinants of exchange rate variability for 21 developed economies in 1980-1998. The results show that traditional criteria implied by the optimum currency area (OCA) theory, such as business cycle synchronisation, trade linkages and economy size, determine to a large extent bilateral exchange rate variability. Using the ordinary least squares estimation, we compute OCA indices for European economies vis-à-vis Germany and identify countries showing consistently large or little signs of convergence. We find that since 1998, most European developed economies have converged to Germany whether or not they are using the euro, suggesting that structural similarity is not driven solely by monetary integration. Our results from the model estimated by the generalized method of moments suggest that two additional criteria reflecting labour market flexibility and private credit growth are significant in explaining the exchange rate variability and lead to a ranking of countries different from the traditional approach. We find a positive relationship between the OCA indices and GDP decline during the economic crisis of 2008-09, which further supports the view that the OCA index is a useful indicator of the candidates' readiness to join the Euro Area. We apply the results to the...
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The globalisation of the Chinese financial sector
Reyisha, Ahemaitijiang ; Teplý, Petr (advisor) ; Havránková, Zuzana (referee)
In this thesis we have studied China's financial sector globalisation by analysing the determinants of Chinese banking sector profitability, and the relationship between GDP growth and FDI inflows. For estimating the Chinese banking sector profitability, we applied system GMM estimation on the annual data of 56 banks currently in China. The time period of the data is from 2002-2011. We found out that both internal and external factors have impact on the Chinese banking sector profitability. As we have expected financial sector globalisation has positive impact on the profitability of banking industry. For analysing the impacts of financial sector globalisation in terms of FDI contribution to the Chinese economy, we have tested the relationship between FDI and GDP by running the VAR model on the macro data over the time period of 1987-2011. We have found that GDP growth explains the rapid development of FDI, and FDI indirectly influences the GDP growth by influencing the domestic investments.
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Foreign Direct Investment and Economic Growth: Evidence from Transition Economies
Su, Qihao ; Holub, Tomáš (advisor) ; Amini, Chiara (referee) ; Semerák, Vilém (referee)
Abstract: Institutional quality and income level of countries can play different role in international trade, which can affect foreign direct investment and economic growth, both negatively and positively. Although the empirical evidence shows a mix result, few literatures specifically study the effect of FDI on economic growth and the role of institutions in FDI and economic growth in developing countries. This thesis is developed on the research of Roodman (2006, 2009) and Farole and Winkler (2012) but specifically focuses on the impacts of institutional quality on FDI-Growth nexus. This thesis is based on absorptive capacity theory and exogenous growth model to utilize dynamic panel GMM techniques robust to instrument proliferation. Finally, the thesis empirically tested the propositions through econometric models by regressing a static panel model and two-stage GMM equation. In summary, based on absorptive capacity theory, this dissertation not only contributes to literature by applying the theoretical model in FDI and economic growth in exploring interaction with the role of institutions and human capital on the FDI-growth nexus but also obtained some new empirical results in different income level groups to explore the impacts of macroeconomics situation that can affect our results. The...
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Can macroprudential policies curb house price booms? International evidence
Šváb, Ondřej ; Horváth, Roman (advisor) ; Geršl, Adam (referee)
This thesis examines the effectiveness of macroprudential policies on reducing housing price growth in the international database of 56 countries with the use of GMM and fixed effects between 2000 and 2017. The macroprudential index is added to the dynamic panel data model where the housing price index is regressed on housing price determinants as the economic growth or unemployment rate. The analysis is also conducted on the sample of countries with a higher market share of owners with a mortgage as there is a higher opportunity to control the housing market through the credit channel. Nevertheless, results show that we do not have enough evidence to state that macroprudential policies curb house price booms. Contrarily, the effect seems to work in the opposite direction which is probably caused by a reverse causality between the growth of real estate prices and the implementation of macroprudential tools. The debt-to-income restriction is the only tool that decreases housing price growth according to the fixed effects model. Detailed counterfactual analysis of the Czech market proposes only a slight impact of the loan-to-value measure on the apartment price development according to one out of four predictions. 1
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Risks to Financial Stability in the Low Interest Rate Environment and its Housing Market Implications: CE Region Study
Meti, Elvira ; Geršl, Adam (advisor) ; Polák, Petr (referee)
iv Abstract The current state of the prolonged low interest rate environment may pose a great threat to the soundness of the financial system both in the eurozone countries as well as in the neighboring regions, such as in countries of Central Europe due to high interconnectedness of markets. Some of the recently identified risks of the low interest rate environment are a notable pickup in mortgage lending and house prices, and deterioration of profitability among banks. We study these channels for the Czech Republic, Hungary and Poland, investigating the impact of the imported ECB monetary policy on local (hos countries) during 2004Q4-2019Q4. Our findings suggest that house prices are further driven by low interest rates, and the effect is lagged by two quarters as looser monetary conditions need time to impact our dependant variables. Furthermore, a decrease in the mortgage rate increases mortgage lending in these countries. Lastly, in our study of 27 banks during 2004-2015, we find that ROAA declines by approximately by 17.8 %, given a one percent increase in the 3-month EURIBOR. Keywords low interest rates, EURIBOR, financial soundness, GMM, residential property, mortgages Author's e-mail 71263908@fsv.cuni.cz Supervisor's e-mail Adam.gersl@gmail.com
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What is the effect of income inequality on economic growth?
Ardeleanu, Dorian ; Baxa, Jaromír (advisor) ; Astapovich, Stanislav (referee)
The impact of income inequality on the level of economic growth is an impor- tant question, but the existing literature did not reach a consensus about the sign of its effect. This thesis studies the impact in 93 countries over the years 1995-2015. We apply two different methods: the fixed effects with Newey and West standard errors, and the first-difference generalized method of moments. The main findings emphasize that a widening wealth gap has an overall negative influence over the real GDP per capita growth. Besides that, the effect is stronger among low-income countries than among high- income ones. Moreover, we find that the impact of income inequality on economic growth depends on the governing party's doctrine. It is negative and statistically significant only in states with centrist governments. 1
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Voice Conversion
Brukner, Jan ; Plchot, Oldřich (referee) ; Černocký, Jan (advisor)
Thesis deals with voice converion. Method, where we want to modify speech parameters of source speaker into that of a target speaker. At the beginning of thesis is described Voice Conversion Challenge (VCC), where participants tried to build better voice conversion systems. In the next part are analysed components of baseline system used in VCC. Modifications which could improve quality of converted voice are proposed. Then is briefly described implementation if these modifications and results are analysed. In the end is part dedicated to further improvements of voice conversion.
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Acoustic Scene Classification from Speech
Dobrotka, Matúš ; Glembek, Ondřej (referee) ; Matějka, Pavel (advisor)
The topic of this thesis is an audio recording classification with 15 different acoustic scene classes that represent common scenes and places where people are situated on a regular basis. The thesis describes 2 approaches based on GMM and i-vectors and a fusion of the both approaches. The score of the best GMM system which was evaluated on the evaluation dataset of the DCASE Challenge is 60.4%. The best i-vector system's score is 68.4%. The fusion of the GMM system and the best i-vector system achieves score of 69.3%, which would lead to the 20th place in the all systems ranking of the DCASE 2017 Challenge (among 98 submitted systems from all over the world).
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The Evolution of Optimum Currency Area Index: Post-crisis Perspective
Kadlecová, Pavlína ; Horváth, Roman (advisor) ; Geršl, Adam (referee)
This paper estimates the determinants of exchange rate variability for 21 developed economies in 1980-1998. The results show that traditional criteria implied by the optimum currency area (OCA) theory, such as business cycle synchronisation, trade linkages and economy size, determine to a large extent bilateral exchange rate variability. Using the ordinary least squares estimation, we compute OCA indices for European economies vis-à-vis Germany and identify countries showing consistently large or little signs of convergence. We find that since 1998, most European developed economies have converged to Germany whether or not they are using the euro, suggesting that structural similarity is not driven solely by monetary integration. Our results from the model estimated by the generalized method of moments suggest that two additional criteria reflecting labour market flexibility and private credit growth are significant in explaining the exchange rate variability and lead to a ranking of countries different from the traditional approach. We find a positive relationship between the OCA indices and GDP decline during the economic crisis of 2008-09, which further supports the view that the OCA index is a useful indicator of the candidates' readiness to join the Euro Area. We apply the results to the...
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