Research of Microphone Array Signal Processing to Audio Signal Separation and Sound Field Reconstruction

Download Research of Microphone Array Signal Processing to Audio Signal Separation and Sound Field Reconstruction PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 144 pages
Book Rating : 4.:/5 (71 download)

DOWNLOAD NOW!


Book Synopsis Research of Microphone Array Signal Processing to Audio Signal Separation and Sound Field Reconstruction by : 吳柏賢

Download or read book Research of Microphone Array Signal Processing to Audio Signal Separation and Sound Field Reconstruction written by 吳柏賢 and published by . This book was released on 2010 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Microphone Array Signal Processing

Download Microphone Array Signal Processing PDF Online Free

Author :
Publisher : Springer Science & Business Media
ISBN 13 : 3540786120
Total Pages : 245 pages
Book Rating : 4.5/5 (47 download)

DOWNLOAD NOW!


Book Synopsis Microphone Array Signal Processing by : Jacob Benesty

Download or read book Microphone Array Signal Processing written by Jacob Benesty and published by Springer Science & Business Media. This book was released on 2008-03-11 with total page 245 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the past few years we have written and edited several books in the area of acousticandspeechsignalprocessing. Thereasonbehindthisendeavoristhat there were almost no books available in the literature when we ?rst started while there was (and still is) a real need to publish manuscripts summarizing the most useful ideas, concepts, results, and state-of-the-art algorithms in this important area of research. According to all the feedback we have received so far, we can say that we were right in doing this. Recently, several other researchers have followed us in this journey and have published interesting books with their own visions and perspectives. The idea of writing a book on Microphone Array Signal Processing comes from discussions we have had with many colleagues and friends. As a c- sequence of these discussions, we came up with the conclusion that, again, there is an urgent need for a monograph that carefully explains the theory and implementation of microphone arrays. While there are many manuscripts on antenna arrays from a narrowband perspective (narrowband signals and narrowband processing), the literature is quite scarce when it comes to s- sor arrays explained from a truly broadband perspective. Many algorithms for speech applications were simply borrowed from narrowband antenna - rays. However, a direct application of narrowband ideas to broadband speech processing may not be necessarily appropriate and can lead to many m- understandings.

Microphone Arrays

Download Microphone Arrays PDF Online Free

Author :
Publisher : Springer Science & Business Media
ISBN 13 : 3662046199
Total Pages : 401 pages
Book Rating : 4.6/5 (62 download)

DOWNLOAD NOW!


Book Synopsis Microphone Arrays by : Michael Brandstein

Download or read book Microphone Arrays written by Michael Brandstein and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 401 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first book to provide a single complete reference on microphone arrays. Top researchers in this field contributed articles documenting the current state of the art in microphone array research, development and technological application.

Theory and Applications of Spherical Microphone Array Processing

Download Theory and Applications of Spherical Microphone Array Processing PDF Online Free

Author :
Publisher : Springer
ISBN 13 : 3319422111
Total Pages : 201 pages
Book Rating : 4.3/5 (194 download)

DOWNLOAD NOW!


Book Synopsis Theory and Applications of Spherical Microphone Array Processing by : Daniel P. Jarrett

Download or read book Theory and Applications of Spherical Microphone Array Processing written by Daniel P. Jarrett and published by Springer. This book was released on 2016-08-26 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the signal processing algorithms that have been developed to process the signals acquired by a spherical microphone array. Spherical microphone arrays can be used to capture the sound field in three dimensions and have received significant interest from researchers and audio engineers. Algorithms for spherical array processing are different to corresponding algorithms already known in the literature of linear and planar arrays because the spherical geometry can be exploited to great beneficial effect. The authors aim to advance the field of spherical array processing by helping those new to the field to study it efficiently and from a single source, as well as by offering a way for more experienced researchers and engineers to consolidate their understanding, adding either or both of breadth and depth. The level of the presentation corresponds to graduate studies at MSc and PhD level. This book begins with a presentation of some of the essential mathematical and physical theory relevant to spherical microphone arrays, and of an acoustic impulse response simulation method, which can be used to comprehensively evaluate spherical array processing algorithms in reverberant environments. The chapter on acoustic parameter estimation describes the way in which useful descriptions of acoustic scenes can be parameterized, and the signal processing algorithms that can be used to estimate the parameter values using spherical microphone arrays. Subsequent chapters exploit these parameters including in particular measures of direction-of-arrival and of diffuseness of a sound field. The array processing algorithms are then classified into two main classes, each described in a separate chapter. These are signal-dependent and signal-independent beamforming algorithms. Although signal-dependent beamforming algorithms are in theory able to provide better performance compared to the signal-independent algorithms, they are currently rarely used in practice. The main reason for this is that the statistical information required by these algorithms is difficult to estimate. In a subsequent chapter it is shown how the estimated acoustic parameters can be used in the design of signal-dependent beamforming algorithms. This final step closes, at least in part, the gap between theory and practice.

Directivity Based Multichannel Audio Signal Processing For Microphones in Noisy Acoustic Environments

Download Directivity Based Multichannel Audio Signal Processing For Microphones in Noisy Acoustic Environments PDF Online Free

Author :
Publisher : Springer
ISBN 13 : 3658251522
Total Pages : 130 pages
Book Rating : 4.6/5 (582 download)

DOWNLOAD NOW!


Book Synopsis Directivity Based Multichannel Audio Signal Processing For Microphones in Noisy Acoustic Environments by : Simon Grimm

Download or read book Directivity Based Multichannel Audio Signal Processing For Microphones in Noisy Acoustic Environments written by Simon Grimm and published by Springer. This book was released on 2019-01-28 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: Simon Grimm examines new multi-microphone signal processing strategies that aim to achieve noise reduction and dereverberation. Therefore, narrow-band signal enhancement approaches are combined with broad-band processing in terms of directivity based beamforming. Previously introduced formulations of the multichannel Wiener filter rely on the second order statistics of the speech and noise signals. The author analyses how additional knowledge about the location of a speaker as well as the microphone arrangement can be used to achieve further noise reduction and dereverberation.

Audio Source Separation and Speech Enhancement

Download Audio Source Separation and Speech Enhancement PDF Online Free

Author :
Publisher : John Wiley & Sons
ISBN 13 : 1119279917
Total Pages : 628 pages
Book Rating : 4.1/5 (192 download)

DOWNLOAD NOW!


Book Synopsis Audio Source Separation and Speech Enhancement by : Emmanuel Vincent

Download or read book Audio Source Separation and Speech Enhancement written by Emmanuel Vincent and published by John Wiley & Sons. This book was released on 2018-07-24 with total page 628 pages. Available in PDF, EPUB and Kindle. Book excerpt: Learn the technology behind hearing aids, Siri, and Echo Audio source separation and speech enhancement aim to extract one or more source signals of interest from an audio recording involving several sound sources. These technologies are among the most studied in audio signal processing today and bear a critical role in the success of hearing aids, hands-free phones, voice command and other noise-robust audio analysis systems, and music post-production software. Research on this topic has followed three convergent paths, starting with sensor array processing, computational auditory scene analysis, and machine learning based approaches such as independent component analysis, respectively. This book is the first one to provide a comprehensive overview by presenting the common foundations and the differences between these techniques in a unified setting. Key features: Consolidated perspective on audio source separation and speech enhancement. Both historical perspective and latest advances in the field, e.g. deep neural networks. Diverse disciplines: array processing, machine learning, and statistical signal processing. Covers the most important techniques for both single-channel and multichannel processing. This book provides both introductory and advanced material suitable for people with basic knowledge of signal processing and machine learning. Thanks to its comprehensiveness, it will help students select a promising research track, researchers leverage the acquired cross-domain knowledge to design improved techniques, and engineers and developers choose the right technology for their target application scenario. It will also be useful for practitioners from other fields (e.g., acoustics, multimedia, phonetics, and musicology) willing to exploit audio source separation or speech enhancement as pre-processing tools for their own needs.

Study and Design of Differential Microphone Arrays

Download Study and Design of Differential Microphone Arrays PDF Online Free

Author :
Publisher : Springer Science & Business Media
ISBN 13 : 3642337538
Total Pages : 184 pages
Book Rating : 4.6/5 (423 download)

DOWNLOAD NOW!


Book Synopsis Study and Design of Differential Microphone Arrays by : Jacob Benesty

Download or read book Study and Design of Differential Microphone Arrays written by Jacob Benesty and published by Springer Science & Business Media. This book was released on 2012-10-22 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microphone arrays have attracted a lot of interest over the last few decades since they have the potential to solve many important problems such as noise reduction/speech enhancement, source separation, dereverberation, spatial sound recording, and source localization/tracking, to name a few. However, the design and implementation of microphone arrays with beamforming algorithms is not a trivial task when it comes to processing broadband signals such as speech. Indeed, in most sensor arrangements, the beamformer output tends to have a frequency-dependent response. One exception, perhaps, is the family of differential microphone arrays (DMAs) who have the promise to form frequency-independent responses. Moreover, they have the potential to attain high directional gains with small and compact apertures. As a result, this type of microphone arrays has drawn much research and development attention recently. This book is intended to provide a systematic study of DMAs from a signal processing perspective. The primary objective is to develop a rigorous but yet simple theory for the design, implementation, and performance analysis of DMAs. The theory includes some signal processing techniques for the design of commonly used first-order, second-order, third-order, and also the general Nth-order DMAs. For each order, particular examples are given on how to form standard directional patterns such as the dipole, cardioid, supercardioid, hypercardioid, subcardioid, and quadrupole. The study demonstrates the performance of the different order DMAs in terms of beampattern, directivity factor, white noise gain, and gain for point sources. The inherent relationship between differential processing and adaptive beamforming is discussed, which provides a better understanding of DMAs and why they can achieve high directional gain. Finally, we show how to design DMAs that can be robust against white noise amplification.

Acoustic Field Analysis in Small Microphone Arrays

Download Acoustic Field Analysis in Small Microphone Arrays PDF Online Free

Author :
Publisher : Logos Verlag Berlin GmbH
ISBN 13 : 3832534539
Total Pages : 156 pages
Book Rating : 4.8/5 (325 download)

DOWNLOAD NOW!


Book Synopsis Acoustic Field Analysis in Small Microphone Arrays by : Roman Scharrer

Download or read book Acoustic Field Analysis in Small Microphone Arrays written by Roman Scharrer and published by Logos Verlag Berlin GmbH. This book was released on 2013 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work, the possibilities of an acoustic field analysis in small microphone arrays are investigated. With the increased use of mobile communication devices, such as smartphones and hearing aids, and the increase in the number of microphones in such devices, multi-channel signal processing has gained popularity. Apart from the definite signal processing, this thesis evaluates what information on the acoustic sound field and environment can be gained from the signal of such small microphone arrays. For this purpose, an innovative sound field classification was developed that determines the energies of the single sound field components. The method is based on spatial coherences of two or more acoustical. The method was successfully verified with a set of simulated and measured input signals. An adaptive automatic sensor mismatch compensation was created, which proved able to fully compensate any slow sensor drift after an initial training. Further, a new method for the blind estimation of the reverberation time based on the dependency of the coherence estimate on the evaluation parameters was proposed. The method determines the reverberation time of a room from the spatial coherence between two or more acoustic sensors.

Acoustic Array Systems

Download Acoustic Array Systems PDF Online Free

Author :
Publisher : John Wiley & Sons
ISBN 13 : 0470828374
Total Pages : 546 pages
Book Rating : 4.4/5 (78 download)

DOWNLOAD NOW!


Book Synopsis Acoustic Array Systems by : Mingsian R. Bai

Download or read book Acoustic Array Systems written by Mingsian R. Bai and published by John Wiley & Sons. This book was released on 2013-03-07 with total page 546 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents a unified framework of far-field and near-field array techniques for noise source identification and sound field visualization, from theory to application. Acoustic Array Systems: Theory, Implementation, and Application provides an overview of microphone array technology with applications in noise source identification and sound field visualization. In the comprehensive treatment of microphone arrays, the topics covered include an introduction to the theory, far-field and near-field array signal processing algorithms, practical implementations, and common applications: vehicles, computing and communications equipment, compressors, fans, and household appliances, and hands-free speech. The author concludes with other emerging techniques and innovative algorithms. Encompasses theoretical background, implementation considerations and application know-how Shows how to tackle broader problems in signal processing, control, and transudcers Covers both farfield and nearfield techniques in a balanced way Introduces innovative algorithms including equivalent source imaging (NESI) and high-resolution nearfield arrays Selected code examples available for download for readers to practice on their own Presentation slides available for instructor use A valuable resource for Postgraduates and researchers in acoustics, noise control engineering, audio engineering, and signal processing.

Sound Capture and Processing

Download Sound Capture and Processing PDF Online Free

Author :
Publisher : John Wiley & Sons
ISBN 13 : 9780470994436
Total Pages : 388 pages
Book Rating : 4.9/5 (944 download)

DOWNLOAD NOW!


Book Synopsis Sound Capture and Processing by : Ivan Jelev Tashev

Download or read book Sound Capture and Processing written by Ivan Jelev Tashev and published by John Wiley & Sons. This book was released on 2009-07-01 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides state-of-the-art algorithms for sound capture, processing and enhancement Sound Capture and Processing: Practical Approaches covers the digital signal processing algorithms and devices for capturing sounds, mostly human speech. It explores the devices and technologies used to capture, enhance and process sound for the needs of communication and speech recognition in modern computers and communication devices. This book gives a comprehensive introduction to basic acoustics and microphones, with coverage of algorithms for noise reduction, acoustic echo cancellation, dereverberation and microphone arrays; charting the progress of such technologies from their evolution to present day standard. Sound Capture and Processing: Practical Approaches Brings together the state-of-the-art algorithms for sound capture, processing and enhancement in one easily accessible volume Provides invaluable implementation techniques required to process algorithms for real life applications and devices Covers a number of advanced sound processing techniques, such as multichannel acoustic echo cancellation, dereverberation and source separation Generously illustrated with figures and charts to demonstrate how sound capture and audio processing systems work An accompanying website containing Matlab code to illustrate the algorithms This invaluable guide will provide audio, R&D and software engineers in the industry of building systems or computer peripherals for speech enhancement with a comprehensive overview of the technologies, devices and algorithms required for modern computers and communication devices. Graduate students studying electrical engineering and computer science, and researchers in multimedia, cell-phones, interactive systems and acousticians will also benefit from this book.

Audio Source Separation

Download Audio Source Separation PDF Online Free

Author :
Publisher : Springer
ISBN 13 : 3319730312
Total Pages : 389 pages
Book Rating : 4.3/5 (197 download)

DOWNLOAD NOW!


Book Synopsis Audio Source Separation by : Shoji Makino

Download or read book Audio Source Separation written by Shoji Makino and published by Springer. This book was released on 2018-03-01 with total page 389 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides the first comprehensive overview of the fascinating topic of audio source separation based on non-negative matrix factorization, deep neural networks, and sparse component analysis. The first section of the book covers single channel source separation based on non-negative matrix factorization (NMF). After an introduction to the technique, two further chapters describe separation of known sources using non-negative spectrogram factorization, and temporal NMF models. In section two, NMF methods are extended to multi-channel source separation. Section three introduces deep neural network (DNN) techniques, with chapters on multichannel and single channel separation, and a further chapter on DNN based mask estimation for monaural speech separation. In section four, sparse component analysis (SCA) is discussed, with chapters on source separation using audio directional statistics modelling, multi-microphone MMSE-based techniques and diffusion map methods. The book brings together leading researchers to provide tutorial-like and in-depth treatments on major audio source separation topics, with the objective of becoming the definitive source for a comprehensive, authoritative, and accessible treatment. This book is written for graduate students and researchers who are interested in audio source separation techniques based on NMF, DNN and SCA.

Audio Signal Processing for Next-Generation Multimedia Communication Systems

Download Audio Signal Processing for Next-Generation Multimedia Communication Systems PDF Online Free

Author :
Publisher : Springer Science & Business Media
ISBN 13 : 1402077696
Total Pages : 375 pages
Book Rating : 4.4/5 (2 download)

DOWNLOAD NOW!


Book Synopsis Audio Signal Processing for Next-Generation Multimedia Communication Systems by : Yiteng (Arden) Huang

Download or read book Audio Signal Processing for Next-Generation Multimedia Communication Systems written by Yiteng (Arden) Huang and published by Springer Science & Business Media. This book was released on 2007-05-08 with total page 375 pages. Available in PDF, EPUB and Kindle. Book excerpt: Audio Signal Processing for Next-Generation Multimedia Communication Systems presents cutting-edge digital signal processing theory and implementation techniques for problems including speech acquisition and enhancement using microphone arrays, new adaptive filtering algorithms, multichannel acoustic echo cancellation, sound source tracking and separation, audio coding, and realistic sound stage reproduction. This book's focus is almost exclusively on the processing, transmission, and presentation of audio and acoustic signals in multimedia communications for telecollaboration where immersive acoustics will play a great role in the near future.

Sound Capture for Human / Machine Interfaces

Download Sound Capture for Human / Machine Interfaces PDF Online Free

Author :
Publisher : Springer Science & Business Media
ISBN 13 : 9783540239543
Total Pages : 292 pages
Book Rating : 4.2/5 (395 download)

DOWNLOAD NOW!


Book Synopsis Sound Capture for Human / Machine Interfaces by : Wolfgang Herbordt

Download or read book Sound Capture for Human / Machine Interfaces written by Wolfgang Herbordt and published by Springer Science & Business Media. This book was released on 2005-03-22 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: With a continuously increasing desire for natural and comfortable human/machine interaction, the acoustic interface of any terminal for multimedia or telecommunication services is challenged to allow seamless and hands-free audio communication. Sound Capture for Human-Machine Interfaces introduces the practical aspects of microphone array signal processing and presents various combinations of beamforming and acoustic echo cancellation.

Parametric Time-Frequency Domain Spatial Audio

Download Parametric Time-Frequency Domain Spatial Audio PDF Online Free

Author :
Publisher : John Wiley & Sons
ISBN 13 : 111925258X
Total Pages : 412 pages
Book Rating : 4.1/5 (192 download)

DOWNLOAD NOW!


Book Synopsis Parametric Time-Frequency Domain Spatial Audio by : Ville Pulkki

Download or read book Parametric Time-Frequency Domain Spatial Audio written by Ville Pulkki and published by John Wiley & Sons. This book was released on 2017-10-04 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive guide that addresses the theory and practice of spatial audio This book provides readers with the principles and best practices in spatial audio signal processing. It describes how sound fields and their perceptual attributes are captured and analyzed within the time-frequency domain, how essential representation parameters are coded, and how such signals are efficiently reproduced for practical applications. The book is split into four parts starting with an overview of the fundamentals. It then goes on to explain the reproduction of spatial sound before offering an examination of signal-dependent spatial filtering. The book finishes with coverage of both current and future applications and the direction that spatial audio research is heading in. Parametric Time-frequency Domain Spatial Audio focuses on applications in entertainment audio, including music, home cinema, and gaming—covering the capturing and reproduction of spatial sound as well as its generation, transduction, representation, transmission, and perception. This book will teach readers the tools needed for such processing, and provides an overview to existing research. It also shows recent up-to-date projects and commercial applications built on top of the systems. Provides an in-depth presentation of the principles, past developments, state-of-the-art methods, and future research directions of spatial audio technologies Includes contributions from leading researchers in the field Offers MATLAB codes with selected chapters An advanced book aimed at readers who are capable of digesting mathematical expressions about digital signal processing and sound field analysis, Parametric Time-frequency Domain Spatial Audio is best suited for researchers in academia and in the audio industry.

Study and Design of Differential Microphone Arrays

Download Study and Design of Differential Microphone Arrays PDF Online Free

Author :
Publisher : Springer
ISBN 13 : 9783642337543
Total Pages : 184 pages
Book Rating : 4.3/5 (375 download)

DOWNLOAD NOW!


Book Synopsis Study and Design of Differential Microphone Arrays by : Jacob Benesty

Download or read book Study and Design of Differential Microphone Arrays written by Jacob Benesty and published by Springer. This book was released on 2012-10-23 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microphone arrays have attracted a lot of interest over the last few decades since they have the potential to solve many important problems such as noise reduction/speech enhancement, source separation, dereverberation, spatial sound recording, and source localization/tracking, to name a few. However, the design and implementation of microphone arrays with beamforming algorithms is not a trivial task when it comes to processing broadband signals such as speech. Indeed, in most sensor arrangements, the beamformer output tends to have a frequency-dependent response. One exception, perhaps, is the family of differential microphone arrays (DMAs) who have the promise to form frequency-independent responses. Moreover, they have the potential to attain high directional gains with small and compact apertures. As a result, this type of microphone arrays has drawn much research and development attention recently. This book is intended to provide a systematic study of DMAs from a signal processing perspective. The primary objective is to develop a rigorous but yet simple theory for the design, implementation, and performance analysis of DMAs. The theory includes some signal processing techniques for the design of commonly used first-order, second-order, third-order, and also the general Nth-order DMAs. For each order, particular examples are given on how to form standard directional patterns such as the dipole, cardioid, supercardioid, hypercardioid, subcardioid, and quadrupole. The study demonstrates the performance of the different order DMAs in terms of beampattern, directivity factor, white noise gain, and gain for point sources. The inherent relationship between differential processing and adaptive beamforming is discussed, which provides a better understanding of DMAs and why they can achieve high directional gain. Finally, we show how to design DMAs that can be robust against white noise amplification.

Microphone Arrays

Download Microphone Arrays PDF Online Free

Author :
Publisher : Springer Nature
ISBN 13 : 3031369742
Total Pages : 232 pages
Book Rating : 4.0/5 (313 download)

DOWNLOAD NOW!


Book Synopsis Microphone Arrays by : Jacob Benesty

Download or read book Microphone Arrays written by Jacob Benesty and published by Springer Nature. This book was released on 2023-08-09 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book explains the motivation for using microphone arrays as opposed to using a single sensor for sound acquisition. The book then goes on to summarize the most useful ideas, concepts, results, and new algorithms therein. The material presented in this work includes analysis of the advantages of using microphone arrays, including dimensionality reduction to remove the redundancy while preserving the variability of the array signals using the principal component analysis (PCA). The authors also discuss benefits such as beamforming with low-rank approximations, fixed, adaptive, and robust distortionless beamforming, differential beamforming, and a new form of binaural beamforming that takes advantage of both beamforming and human binaural hearing properties to improve speech intelligibility. The book makes the microphone array signal processing theory and applications available in a complete and self-contained text. The authors attempt to explain the main ideas in a clear and rigorous way so that the reader can easily capture the potentials, opportunities, challenges, and limitations of microphone array signal processing. This book is written for those who work on the topics of microphone arrays, noise reduction, speech enhancement, speech communication, and human-machine speech interfaces.

A Study into the Design of Steerable Microphone Arrays

Download A Study into the Design of Steerable Microphone Arrays PDF Online Free

Author :
Publisher : Springer
ISBN 13 : 9811016917
Total Pages : 122 pages
Book Rating : 4.8/5 (11 download)

DOWNLOAD NOW!


Book Synopsis A Study into the Design of Steerable Microphone Arrays by : Chiong Ching Lai

Download or read book A Study into the Design of Steerable Microphone Arrays written by Chiong Ching Lai and published by Springer. This book was released on 2016-08-13 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book covers the design formulations for broadband beamformer targeting nearfield and farfield sources. The book content includes background information on the acoustic environment, including propagation medium, the array geometries, signal models and basic beamformer designs. Subsequently it introduces design formulation for nearfield, farfield and mixed nearfield-farfield beamformers and extends the design formulation into electronically steerable beamformers. In addition, a robust formulation is introduced for all the designs mentioned.