Effects of Lombard Reflex on the Performance of Deep-Learning-Based Audio-Visual Speech Enhancement Systems

Humans tend to change their way of speaking when they are immersed in a noisy environment, a reflex known as Lombard effect. Current speech enhancement systems based on deep learning do not usually take into account this change in the speaking style, because they are trained with neutral (non-Lombard) speech utterances recorded under quiet conditions to which noise is artificially added. In this paper, we investigate the effects that the Lombard reflex has on the performance of audio-visual speech enhancement systems based on deep learning. The results show that a gap in the performance of as much as approximately 5 dB between the systems trained on neutral speech and the ones trained on Lombard speech exists. This indicates the benefit of taking into account the mismatch between neutral and Lombard speech in the design of audio-visual speech enhancement systems

Sources of the Great Moderation: shocks, frictions, or monetary policy?

We study the sources of the Great Moderation by estimating a variety of medium-scale dynamic stochastic general equilibrium (DSGE) models that incorporate regime switches in shock variances and the inflation target. The best-fit model—the one with two regimes in shock variances—gives quantitatively different dynamics compared with the benchmark constant-parameter model. Our estimates show that three kinds of shocks accounted for most of the Great Moderation and business-cycle fluctuations: capital depreciation shocks, neutral technology shocks, and wage markup shocks. In contrast to the existing literature, we find that changes in the inflation target or shocks in the investment-specific technology played little role in macroeconomic volatility. Moreover, our estimates indicate considerably fewer nominal rigidities than the literature suggests.Econometric models

Asymmetric expectation effects of regime shifts and the Great Moderation

We assess the quantitative importance of the expectation effects of regime shifts in monetary policy in a DSGE model that allows the monetary policy rule to switch between a ?bad? regime and a ?good? regime. When agents take into account such regime shifts in forming expectations, the expectation effect is asymmetric across regimes. In the good regime, the expectation effect is small despite agents? disbelief that the regime will last forever. In the bad regime, however, the expectation effect on equilibrium dynamics of inflation and output is quantitatively important, even if agents put a small probability that monetary policy will switch to the good regime. Although the expectation effect dampens aggregate fluctuations in the bad regime, a switch from the bad regime to the good regime can still substantially reduce the volatility of both inflation and output, provided that we allow some ?reduced-form? parameters in the private sector to change with monetary policy regime. Much of the volatility reduction is attributed to a structural break in the persistence of equilibrium dynamics of macroeconomic variables.Monetary policy ; Inflation (Finance)

Asymmetric expectation effects of regime shifts and the Great Moderation

The possibility of regime shifts in monetary policy can have important effects on rational agents' expectation formation and equilibrium dynamics. In a dynamic stochastic general equilibrium model where the monetary policy rule switches between a dovish regime that accommodates inflation and a hawkish regime that stabilizes inflation, the expectation effect is asymmetric across regimes. Such an asymmetric effect makes it difficult but still possible to generate substantial reductions in the volatilities of inflation and output as the monetary policy switches from the dovish regime to the hawkish one.

Sources of the Great Moderation: shocks, friction, or monetary policy?

We study the sources of the Great Moderation by estimating a variety of medium-scale DSGE models that incorporate regime switches in shock variances and in the inflation target. The best-fit model, the one with two regimes in shock variances, gives quantitatively different dynamics in comparison with the benchmark constant-parameter model. Our estimates show that three kinds of shocks accounted for most of the Great Moderation and business-cycle fluctuations: capital depreciation shocks, neutral technology shocks, and wage markup shocks. In contrast to the existing literature, we find that changes in the inflation target or shocks in the investment-specific technology played little role in macroeconomic volatility. Moreover, our estimates indicate much less nominal rigidities than those suggested in the literature.Econometric models ; Business cycles