An investigation of the utility of monaural sound source separation via nonnegative matrix factorization applied to acoustic echo and reverberation mitigation for hands-free telephony

In this thesis we investigate the applicability and utility of Monaural Sound Source Separation (MSSS) via Nonnegative Matrix Factorization (NMF) for various problems related to audio for hands-free telephony. We first investigate MSSS via NMF as an alternative acoustic echo reduction approach to existing approaches such as Acoustic Echo Cancellation (AEC). To this end, we present the single-channel acoustic echo problem as an MSSS problem, in which the objective is to extract the users signal from a mixture also containing acoustic echo and noise. To perform separation, NMF is used to decompose the near-end microphone signal onto the union of two nonnegative bases in the magnitude Short Time Fourier Transform domain. One of these bases is for the spectral energy of the acoustic echo signal, and is formed from the in- coming far-end user’s speech, while the other basis is for the spectral energy of the near-end speaker, and is trained with speech data a priori. In comparison to AEC, the speaker extraction approach obviates Double-Talk Detection (DTD), and is demonstrated to attain its maximal echo mitigation performance immediately upon initiation and to maintain that performance during and after room changes for similar computational requirements. Speaker extraction is also shown to introduce distortion of the near-end speech signal during double-talk, which is quantified by means of a speech distortion measure and compared to that of AEC. Subsequently, we address Double-Talk Detection (DTD) for block-based AEC algorithms. We propose a novel block-based DTD algorithm that uses the available signals and the estimate of the echo signal that is produced by NMF-based speaker extraction to compute a suitably normalized correlation-based decision variable, which is compared to a fixed threshold to decide on doubletalk. Using a standard evaluation technique, the proposed algorithm is shown to have comparable detection performance to an existing conventional block-based DTD algorithm. It is also demonstrated to inherit the room change insensitivity of speaker extraction, with the proposed DTD algorithm generating minimal false doubletalk indications upon initiation and in response to room changes in comparison to the existing conventional DTD. We also show that this property allows its paired AEC to converge at a rate close to the optimum. Another focus of this thesis is the problem of inverting a single measurement of a non- minimum phase Room Impulse Response (RIR). We describe the process by which percep- tually detrimental all-pass phase distortion arises in reverberant speech filtered by the inverse of the minimum phase component of the RIR; in short, such distortion arises from inverting the magnitude response of the high-Q maximum phase zeros of the RIR. We then propose two novel partial inversion schemes that precisely mitigate this distortion. One of these schemes employs NMF-based MSSS to separate the all-pass phase distortion from the target speech in the magnitude STFT domain, while the other approach modifies the inverse minimum phase filter such that the magnitude response of the maximum phase zeros of the RIR is not fully compensated. Subjective listening tests reveal that the proposed schemes generally produce better quality output speech than a comparable inversion technique

An investigation of the utility of monaural sound source separation via nonnegative matrix factorization applied to acoustic echo and reverberation mitigation for hands-free telephony

In this thesis we investigate the applicability and utility of Monaural Sound Source Separation (MSSS) via Nonnegative Matrix Factorization (NMF) for various problems related to audio for hands-free telephony. We first investigate MSSS via NMF as an alternative acoustic echo reduction approach to existing approaches such as Acoustic Echo Cancellation (AEC). To this end, we present the single-channel acoustic echo problem as an MSSS problem, in which the objective is to extract the users signal from a mixture also containing acoustic echo and noise. To perform separation, NMF is used to decompose the near-end microphone signal onto the union of two nonnegative bases in the magnitude Short Time Fourier Transform domain. One of these bases is for the spectral energy of the acoustic echo signal, and is formed from the in- coming far-end user’s speech, while the other basis is for the spectral energy of the near-end speaker, and is trained with speech data a priori. In comparison to AEC, the speaker extraction approach obviates Double-Talk Detection (DTD), and is demonstrated to attain its maximal echo mitigation performance immediately upon initiation and to maintain that performance during and after room changes for similar computational requirements. Speaker extraction is also shown to introduce distortion of the near-end speech signal during double-talk, which is quantified by means of a speech distortion measure and compared to that of AEC. Subsequently, we address Double-Talk Detection (DTD) for block-based AEC algorithms. We propose a novel block-based DTD algorithm that uses the available signals and the estimate of the echo signal that is produced by NMF-based speaker extraction to compute a suitably normalized correlation-based decision variable, which is compared to a fixed threshold to decide on doubletalk. Using a standard evaluation technique, the proposed algorithm is shown to have comparable detection performance to an existing conventional block-based DTD algorithm. It is also demonstrated to inherit the room change insensitivity of speaker extraction, with the proposed DTD algorithm generating minimal false doubletalk indications upon initiation and in response to room changes in comparison to the existing conventional DTD. We also show that this property allows its paired AEC to converge at a rate close to the optimum. Another focus of this thesis is the problem of inverting a single measurement of a non- minimum phase Room Impulse Response (RIR). We describe the process by which percep- tually detrimental all-pass phase distortion arises in reverberant speech filtered by the inverse of the minimum phase component of the RIR; in short, such distortion arises from inverting the magnitude response of the high-Q maximum phase zeros of the RIR. We then propose two novel partial inversion schemes that precisely mitigate this distortion. One of these schemes employs NMF-based MSSS to separate the all-pass phase distortion from the target speech in the magnitude STFT domain, while the other approach modifies the inverse minimum phase filter such that the magnitude response of the maximum phase zeros of the RIR is not fully compensated. Subjective listening tests reveal that the proposed schemes generally produce better quality output speech than a comparable inversion technique

Anti-computing

We live in a moment of high anxiety around digital transformation. Computers are blamed for generating toxic forms of culture and ways of life. Once part of future imaginaries that were optimistic or even utopian, today there is a sense that things have turned out very differently. Anti-computing is widespread. This book seeks to understand its cultural and material logics, its forms, and its operations. Anti-Computing critically investigates forgotten histories of dissent – moments when the imposition of computational technologies, logics, techniques, imaginaries, utopias have been questioned, disputed, or refused. It asks why dissent is forgotten and how - under what circumstances - it revives. Constituting an engagement with media archaeology/medium theory and working through a series of case studies, this book is compelling reading for scholars in digital media, literary, cultural history, digital humanities and associated fields at all levels

Anti-computing

Anti-computing explores forgotten histories and contemporary forms of dissent – moments when the imposition of computational technologies, logics, techniques, imaginaries, utopias have been questioned, disputed, or refused. It also asks why these moments tend to be forgotten. What is it about computational capitalism that means we live so much in the present? What has this to do with computational logics and practices themselves? This book addresses these issues through a critical engagement with media archaeology and medium theory and by way of a series of original studies; exploring Hannah Arendt and early automation anxiety, witnessing and the database, Two Cultures from the inside out, bot fear, singularity and/as science fiction. Finally, it returns to remap long-standing concerns against new forms of dissent, hostility, and automation anxiety, producing a distant reading of contemporary hostility.At once an acute response to urgent concerns around toxic digital cultures, an accounting with media archaeology as a mode of medium theory, and a series of original and methodologically fluid case studies, this book crosses an interdisciplinary research field including cultural studies, media studies, medium studies, critical theory, literary and science fiction studies, media archaeology, medium theory, cultural history, technology history

Anti-computing

Anti-computing explores forgotten histories and contemporary forms of dissent – moments when the imposition of computational technologies, logics, techniques, imaginaries, utopias have been questioned, disputed, or refused. It also asks why these moments tend to be forgotten. What is it about computational capitalism that means we live so much in the present? What has this to do with computational logics and practices themselves? This book addresses these issues through a critical engagement with media archaeology and medium theory and by way of a series of original studies; exploring Hannah Arendt and early automation anxiety, witnessing and the database, Two Cultures from the inside out, bot fear, singularity and/as science fiction. Finally, it returns to remap long-standing concerns against new forms of dissent, hostility, and automation anxiety, producing a distant reading of contemporary hostility.At once an acute response to urgent concerns around toxic digital cultures, an accounting with media archaeology as a mode of medium theory, and a series of original and methodologically fluid case studies, this book crosses an interdisciplinary research field including cultural studies, media studies, medium studies, critical theory, literary and science fiction studies, media archaeology, medium theory, cultural history, technology history

Proceedings of the 21st International Congress of Aesthetics, Possible Worlds of Contemporary Aesthetics Aesthetics Between History, Geography and Media

The Faculty of Architecture, University of Belgrade and the Society for Aesthetics of Architecture and Visual Arts of Serbia (DEAVUS) are proud to be able to organize the 21st ICA Congress on “Possible Worlds of Contemporary Aesthetics: Aesthetics Between History, Geography and Media”. We are proud to announce that we received over 500 submissions from 56 countries, which makes this Congress the greatest gathering of aestheticians in this region in the last 40 years. The ICA 2019 Belgrade aims to map out contemporary aesthetics practices in a vivid dialogue of aestheticians, philosophers, art theorists, architecture theorists, culture theorists, media theorists, artists, media entrepreneurs, architects, cultural activists and researchers in the fields of humanities and social sciences. More precisely, the goal is to map the possible worlds of contemporary aesthetics in Europe, Asia, North and South America, Africa and Australia. The idea is to show, interpret and map the unity and diverseness in aesthetic thought, expression, research, and philosophies on our shared planet. Our goal is to promote a dialogue concerning aesthetics in those parts of the world that have not been involved with the work of the International Association for Aesthetics to this day. Global dialogue, understanding and cooperation are what we aim to achieve. That said, the 21st ICA is the first Congress to highlight the aesthetic issues of marginalised regions that have not been fully involved in the work of the IAA. This will be accomplished, among others, via thematic round tables discussing contemporary aesthetics in East Africa and South America. Today, aesthetics is recognized as an important philosophical, theoretical and even scientific discipline that aims at interpreting the complexity of phenomena in our contemporary world. People rather talk about possible worlds or possible aesthetic regimes rather than a unique and consistent philosophical, scientific or theoretical discipline

Initial human dispersal and native fauna at the South American southern cone, Argentina. An example case from the revision of the fossil collections

La falta de registres directes com intervencions biològiques (marques de tall i marques de carnívors) no ha permès la discussió de com serien les relacions paleoecològiques de competència i depredació entre humans, megaherbívors i carnívors durant la primera dispersió humana a les Amèriques. Buscar aquest tipus d’informació en fonts no tradicionals dins de la investigació arqueològica, com les col•leccions vuitcentistes de fauna nativa, és una manera alternativa d’obtenir dades. Aquesta temàtica permet entendre com Homo sapiens intervingué en un ecosistema natiu establert i que mai havia estat alterat per la presencia homínida. El primer poblament humà a les Amèriques pot ser caracteritzat com a invasiu, ja que aquesta espècie no nativa va tenir una ràpida dispersió. Es va fer ús de la tafonomia per diferenciar intervencions biològiques, d’altre tipus de modificacions. A partir de les espècies registrades amb marques biològiques, els humans haurien depredat (i/o carronyejat) sobre especies que posseïen defenses desenvolupades per confrontar carnívors holàrtics (gigantisme en el cas de Megatherium americanum o cuirassa en Glyptodontidae) mentre que especies més petites dins la megafauna (Mylodontidae) haurien estat explotades per carnívors i humans. Així els carnívors haurien aprofitat alguns taxons d’aquesta megafauna en diferents moments del Pleistocè. Aquesta situació es va mantenir malgrat les fluctuacions ambientals. Al final d’aquest període, l’ingrés d’ Homo sapiens, va suposar afegir un nou carnívor en la cadena tròfica, que hauria depredat una major varietat d’espècies, moltes d’elles no explotades pels carnívors presents. Els grups humans haurien modificat els nitxos ecològics existents i colonitzat les vacants afectant les relacions de competència i depredació establerta. Aquest fet va provocar impactes directes i indirectes en la cadena tròfica nativa, que a llarg termini hauria afectat la sostenibilitat d’aquest ecosistema.La escasez de registros directos como intervenciones biológicas (huellas de corte y marcas de carnívoros) no ha permitido la discusión de cómo serían las relaciones paleoecológicas de competencia y depredación entre humanos, megaherbívoros y carnívoros durante la primera dispersión humana en las Américas. Buscar este tipo de información en fuentes no tradicionales dentro de la investigación arqueológica, como las colecciones decimonónicas de fauna nativa, es una manera alternativa de obtener datos. Esta temática permite entender cómo Homo sapiens intervino en un ecosistema nativo establecido y que nunca había sido alterado por la presencia homínida. El primer poblamiento humano en las Américas puede ser caracterizado como de invasivo, ya que esta especie no nativa tuvo una rápida dispersión. Se hizo uso de la tafonomía para diferenciar intervenciones biológicas, de otro tipo de modificaciones. A partir de las especies registradas con marcas biológicas, los humanos habrían depredado (y/o carroñado) sobre especies que poseían defensas desarrolladas para confrontar carnívoros holárticos (gigantismo en el caso de Megatherium americanum o coraza en Glyptodontidae) mientras que especies más pequeñas dentro de la megafauna (Mylodontidae) habrían sido explotada por carnívoros y humanos. Así los carnívoros habrían aprovechado algunos taxones de esta megafauna en distintos momentos del Pleistoceno. Esta situación se mantuvo a pesar de las fluctuaciones ambientales. Al final de este período, el ingreso de Homo sapiens, supuso añadir un nuevo carnívoro en la cadena trófica, que habría depredado una mayor variedad de especies, muchas de ellas, no explotadas por los carnívoros presentes. Los grupos humanos habrían modificado los nichos ecológicos existentes y colonizado los vacantes, afectando las relaciones de competencia y depredación establecidas. Esto provocó impactos directos e indirectos en la cadena trófica nativa, lo que a largo plazo habría afectado la sustentabilidad de este ecosistema.The scarcity of direct evidence as biological interventions (cut maks or carnivore marks) made difficult the discussion of how paleoecological relationships (e.g.. depredation an competition) should have been between humans, megaherbivores and carnivores during first humans’ dispersal in the Americas. To search this type of evidence in non-traditional archaeological sources, such as nineteenth collections of native fauna, is an alternative way to obtain information. This allows the understanding of how Homo sapiens has intervened in the established native ecosystem that has never been changed by hominid presence. First human dispersal in the Americas can be characterized as invasive, as this non-native species had a fast dispersion. Taphonomy was used to differentiate biological interventions from other types of modifications. Considering the identified species with biological marks, humans should have depredate (or scavenge) over species that possessed defences to confront holartic carnivores (gigantism in Megatherium americanum case or armor in Glyptodontidae case). Smaller species of the megafauna, such as Mylodontidae, should have been exploited by carnivores and humans. Therefore carnivores should have consumed some taxa of the megafauna in different moments of the Pleistocene period. This situation was sustained thought time despite environmental fluctuations. At the end of the Pleistocene, Homo sapiens entrance should have implied the addition of a new carnivore in the trophic chain. This new species had depredated over a major variety of fauna, even those ones not exploited by the native carnivores. Humans should have modified the existing ecological niches and colonized the empty ones affecting the established competition and depredation relationships. This provoked direct and indirect impacts in the native trophic chain. In long term, this situation should have affected the sustainability of this ecosystem