Wouter Tirry

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During the transition to wideband speech telephony, artificial bandwidth extension (ABE) could help to preserve customer satisfaction by enhancing speech quality in case of narrowband (NB) calls. However, the assessment of speech quality for ABE systems is still an open question. In the literature, instrumental measures are often used to judge the quality(More)
In this contribution we propose an a priori signal-to-noise ratio (SNR) estimator based on a probabilistic speech model. Since the a priori SNR is an important means for speech enhancement algorithms, such as weighting rule calculation for noise reduction or speech presence probability computation, its diligent estimation is of wide interest. As a basis for(More)
In studies on artificial bandwidth extension (ABE), there is a lack of international coordination in subjective tests between multiple methods and languages. Here we present the design of absolute category rating listening tests evaluating 12 ABE variants of six approaches in multiple languages, namely in American English, Chinese, German, and Korean. Since(More)
As the a priori signal-to-noise ratio SNR contains crucial information about a signal's mixture of speech and noise, its estimation is subject to steady research. In this paper, we introduce a novel a priori SNR estimator based on synthesizing an idealized excitation signal in the cepstral domain. Our approach utilizes a source-filter decomposition in(More)
Various studies have shown that the instrumental measures wideband PESQ and POLQA are not reliably predicting speech quality for artificial speech bandwidth extension ABE test conditions, as this has never been their scope. Based on data from a coordinated subjective listening test with 12 ABE variants developed by 6 different institutions, conducted in 4(More)
Among different microphone array processing techniques, data-dependent beamforming has been proven to be effective in suppressing ambient noise. When applied for dereverberation, however, the adaptation process results in a biased estimate of the beamformer coefficients leading to strong distortions at the beamformer output. In this paper, we investigate(More)
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