Digital Systems: Hardware Organization and Design Introduction

Digital Systems: Hardware Organization and Design Introduction
11/13/2018 Speech Processing Introduction Architecture of a Respresentative 32 Bit Processor

Digital Systems: Hardware Organization and Design
11/13/2018 Syllabus ECE 5525 Speech Processing Contact Info: Këpuska, Veton Olin Engineering Building, Office # 353 Tel. (321) CRN Subj Crse Sec Credits Title ECE 5525 E1 3.00 Speech Processing Instructor(s): Veton Këpuska Textbook(s): “Discrete-Time Speech Signal Processing: Principles and Practice”, Thomas F.Quatieri, Prentice Hall, 2002 “Theory and Applications of Digital Speech Processing”, Lawrence R. Rabiner, Ronald W. Schafer, Prentice Hall, 2011 Reference Material: “Digital Processing of Speech Signals”, L.R. Rabiner and R.W. Schafer, Prentice Hall, 1978 “Digital Signal Processing”, Alan V. Oppenheim and Ronald W. Schafer, Prentice Hall, 1975 “Digital Signal Processing A Practical Approach”, Emmanuel C. Ifeachor and Barrie W. Jervis, Second Edition, Prentice Hall, 2002 13 November 2018 Veton Këpuska Architecture of a Respresentative 32 Bit Processor

11/13/2018 Syllabus Course Goals: Teach modern methods that are used to process speech signals. Subject Area: Digital Speech Processing Prerequisites by Topic: Digital Signal Processing Topics Covered: Discrete-Time Speech Signal Processing, Production and Classification of Speech Sounds, Acoustic Theory of Speech Production, Speech Perception, Speech Analysis, Speech Synthesis, Homomorphic Speech Processing, Short-Time Fourier Transform Analysis and Synthesis, Filter-Bank Analysis/Synthesis, Sinusoidal Analysis/Synthesis, Frequency Domain-Pitch Estimation, Nonlinear Measurement and Modeling Techniques Coding of Speech Signals, Speech Enhancement, Speaker Recognition, Methods for Speech Recognition, Digital Speech Processing for Man-Machine Communication by Voice Recommended Grading Homework: 20% Exams: 30% Project(s): 50% MATLAB Exercises and Homework Problems 13 November 2018 Veton Këpuska Architecture of a Respresentative 32 Bit Processor

11/13/2018 Course Information or Directly 13 November 2018 Veton Këpuska Architecture of a Respresentative 32 Bit Processor

Discrete-Time Speech Signal Processing
Introduction 13 November 2018 Veton Këpuska

Introduction The topic of this study is as old as our human language and as new as the newest computer chip. Goal of creation of more efficient and effective systems for: human-to-human communication, as well as More recently human-machine communication, is studied. 13 November 2018 Veton Këpuska

History 1960’s Digital Signal Processing (DSP):
Assumed a central role in speech communication studies: It enabled development of a large number of applications Advances in IC technology DSP algorithms Computer architecture 13 November 2018 Veton Këpuska

History Created environment with virtually limitless opportunities for innovation in Speech Processing Image Processing Video Processing Radar & Sonar Medical Diagnostics, and Consumer Electronics 13 November 2018 Veton Këpuska

11/13/2018 History Three levels of understanding are required to appreciate the technological advancement of DSP Theoretical Conceptual Practical Practice Concepts Theory Ability to implement theory and concepts in working code (MATLAB, C, C++, JAVA) Basic understanding of how theory is applied Mathematics, derivations, signal processing 13 November 2018 Veton Këpuska Architecture of a Respresentative 32 Bit Processor

Speech Technology Theoretical: Acoustic Theory of Speech Production
The basic Mathematics of Speech Signal representation. Derivation of Various Properties of Speech associated with each representation Basic Signal Processing mathematics: Speech signal Sampling Aliasing Filtering and other DSP methods 13 November 2018 Veton Këpuska

Speech Technology Conceptual
Speech Processing theory is applied in order to make various speech measurements and to estimate and quantify various attributes of the speech signal 13 November 2018 Veton Këpuska

Speech Technology Practical
For technology to realize its full potential, it is essential to be able to convert theory and conceptual understanding to practice. This process involves constraints: Knowledge of the goals of the application Knowledge of the engineering tradeoffs and judgments, and Ability to provide implementations in working computer code (e.g., MATLAB, C/C++ or java, etc.), Specialized code running in real-time signal-processing chips Specialized languages and technologies such as: ASICs FPGAs (Field Programmable Gate Arrays) DSP chips 13 November 2018 Veton Këpuska

Speech Technology What is the nature of speech signal?
How do DPS techniques play a role in learning about the speech signal? What are the basic digital representations of speech signal and how are they used in algorithms for speech processing? What are the important applications that are enabled by digital speech processing methods? 13 November 2018 Veton Këpuska

Digital Systems: Hardware Organization and Design 11/13/2018 Discrete-Time Speech Signal Processing Speech has “evolved” as a primary form of communication between humans. Technological advancement has enhanced our ability to communicate: One early case is the transduction by a telephone handset of the continuously-varying speech pressure signal at the lips output to continuously-varying (analog) electric voltage signal. Digital technology has brought communication to a new level. This technology requires additional transduction of the signals: Analog-to-digital (A/D) and Digital-to-Analog converter (D/A), vs Continuous Analog Signal 13 November 2018 Veton Këpuska Architecture of a Respresentative 32 Bit Processor

Digital Systems: Hardware Organization and Design 11/13/2018 Discrete-Time Speech Signal Processing The topic of this course can be loosely defined as: The manipulation of sampled speech signals by a digital processor to obtain a new signal with some desired properties. Example: Changing a speaker’s rate of articulation with the use of digital computer. Modification of articulation rate (referred to as time-scale modification of speech) has as an objective to: generate a new speech waveform that corresponds to a person talking faster or slower than the original rate, maintain the character of the speaker’s voice (i.e., there should be little change in the pitch and spectrum of the original utterance). 13 November 2018 Veton Këpuska Architecture of a Respresentative 32 Bit Processor

Time-Scale Modification Example
Digital Systems: Hardware Organization and Design 11/13/2018 Time-Scale Modification Example Useful applications: Fast Scanning of a long recording in a message playback system. Slowing Down difficult to understand speech. 13 November 2018 Veton Këpuska Architecture of a Respresentative 32 Bit Processor

The Speech-Communication Pathway
Digital Systems: Hardware Organization and Design 11/13/2018 The Speech-Communication Pathway The linguistic level of communication: (ECE 5527 & ECE 5526) Idea is first formed in the mind of the speaker. This idea is then transformed to words, phrases, and sentences according to the grammatical rules of the language. The physiological level of communication: The brain creates electric signals that move along the motor nerves these electric signals activate muscles in the vocal tract and vocal cords. 13 November 2018 Veton Këpuska Architecture of a Respresentative 32 Bit Processor

The acoustic level in speech communication pathway: (ECE 5525) This vocal tract and vocal cord movement results in pressure changes within the vocal tract, and, in particular, at the lips initiating a sound wave that propagates in space. Pressure changes at the ear canal cause vibrations at the ear drum of the listener. 13 November 2018 Veton Këpuska

Digital Systems: Hardware Organization and Design 11/13/2018 The Speech-Communication Pathway The physiological level of communication pathway: Eardrum vibrations induce electric signals that move along the sensory nerves to the brain. The linguistic level of the listener: The brain performs speech recognition and understanding. The linguistic and physiological activity of: The speaker => “transmitter” The listener => “receiver” 13 November 2018 Veton Këpuska Architecture of a Respresentative 32 Bit Processor

Digital Systems: Hardware Organization and Design 11/13/2018 The Speech-Communication Pathway Transmitter and Receiver of the speech-communication system have other functions besides basic communication: Monitoring and correction of one’s own speech via the feedback through speakers ear (importance of the feedback studied in the speech of the deaf). Control of articulation rate Adaptation of speech production to mimic voices, etc. Receiver performs voice recognition: Robust to noise and other interferences Able to focus on a single low-volume speaker in a room full with louder interfering multiple speakers (cocktail party effect). 13 November 2018 Veton Këpuska Architecture of a Respresentative 32 Bit Processor

Digital Systems: Hardware Organization and Design 11/13/2018 The Speech-Communication Pathway Significant advances in reproducing parts of this communication system by synthetic means. Far from emulating the human communication system. 13 November 2018 Veton Këpuska Architecture of a Respresentative 32 Bit Processor

Speech Communication Pathway (From Rabiner Schafer Book)
13 November 2018 Veton Këpuska

Analysis/Synthesis Based on Speech Production and Perception
Digital Systems: Hardware Organization and Design 11/13/2018 Analysis/Synthesis Based on Speech Production and Perception This class does not cover entire speech communication pathway: Signal measurements of the acoustic waveform. From these measurements and current understanding of speech of how the vocal tract and vocal cords produce sound waves production models are build. Starting from analog representations which are then transformed to discrete-time representations (A/D). From the receiver side the signal processing of the ear and higher auditory levels are covered however to significantly lesser extend only to account for the effect of speech processing on perception. 13 November 2018 Veton Këpuska Architecture of a Respresentative 32 Bit Processor

Applications: Coding, Synthesis, Recognition, …
Speech Stack Applications: Coding, Synthesis, Recognition, … Processing Algorithms: Speech/silence detection (VAD), pitch detection. Formant analysis, … Signal Representation: Temporal, short-time spectrum, homomorphic processing, linear predictive analysis, … Fundamental Science/Technology: DSP theory, Acoustic, Linguistic, Perception 13 November 2018 Veton Këpuska

Digital Systems: Hardware Organization and Design 11/13/2018 Analysis/Synthesis Based on Speech Production and Perception Preview of a speech model. Figure in the slide shows the sound production and perception pathway. 13 November 2018 Veton Këpuska Architecture of a Respresentative 32 Bit Processor

In a vowel production: Air is forced from the lungs (by contraction of the muscles around the lung cavity). 13 November 2018 Veton Këpuska

In a vowel production: Air then flows pass the vocal cord/folds (two masses of flesh) causing periodic vibration of the cords. 13 November 2018 Veton Këpuska

In a vowel production: The rate of vibration of the cords determines the pitch of the sound. Periodic puffs caused by vibration of cords act as an excitation input, or source, to the vocal tract. The vocal tract is the cavity between the vocal cords and the lips: Vocal tract acts as a resonator that spectrally shapes the periodic input (much like the cavity of the musical wind instrument). 13 November 2018 Veton Këpuska

Vowel Production: 13 November 2018 Veton Këpuska

Vowel Formant Chart 13 November 2018 Veton Këpuska

Digital Systems: Hardware Organization and Design 11/13/2018 Analysis/Synthesis Based on Speech Production and Perception 13 November 2018 Veton Këpuska Architecture of a Respresentative 32 Bit Processor

Digital Systems: Hardware Organization and Design 11/13/2018 Analysis/Synthesis Based on Speech Production and Perception From this basic understanding of the speech production mechanism a simple engineering model can be build, referred to source/filter model. In this model the following is assumed: Vocal tract is a liner time-invariant system (or filter), This linear time-invariant system is driven by a periodic impulse-like input. Those assumptions imply that the output at the lips that is itself periodic. 13 November 2018 Veton Këpuska Architecture of a Respresentative 32 Bit Processor

Digital Systems: Hardware Organization and Design 11/13/2018 Analysis/Synthesis Based on Speech Production and Perception Example of a vowel is “a” as in the word “father”. Vowel “a” is one of many basic sounds of a language - called phonemes. For each phoneme a different production model is built. Typical speech utterance consists of a string of vowel and consonant phonemes whose temporal and spectral characteristics change with time. This change corresponds to the changes in excitation source and vocal tract system. This fact implies: A time-varying source and system, Furthermore, in realty there is a complex non-linear interaction of both. Therefore, even though a simple linear time-invariant model seems plausible, it does not always represent well the real system. 13 November 2018 Veton Këpuska Architecture of a Respresentative 32 Bit Processor

English Phoneme Chart 13 November 2018 Veton Këpuska

Digital Systems: Hardware Organization and Design 11/13/2018 Analysis/Synthesis Based on Speech Production and Perception Using discrete-time modeling of speech production the course will cover the design of speech analysis/synthesis systems as depicted in Figure 1.3. Analysis part extracts underlying parameters of time-varying model from speech waveform. Synthesis takes extracted parameters and models to put back together the speech waveform. An objective in this development is to achieve an identity system for which the output equals to input when no manipulation is performed. A number of other analysis/synthesis methods can be derived based on various useful mathematical representations in time or frequency. These analysis/synthesis methods are the backbone for applications that transform the speech waveform into some desirable form. 13 November 2018 Veton Këpuska Architecture of a Respresentative 32 Bit Processor

Applications (Project Areas)
Digital Systems: Hardware Organization and Design 11/13/2018 Applications (Project Areas) Speech Modification: time-scale manipulations: Fitting the speech waveform - In Radio and TV commercials into an allocated time slot and the synchronization of audio and video presentation. Speeding up speech – Message playback Voice mail Reading machines and books for the blind Slowing down speech – Learning a foreign language Voice transformations using Pitch and spectral changes of speech signal: Voice disguise Entertainment Speech synthesis Spectral change of frequency compression and expansion: may be useful in transforming speech as an aid to the partially deaf. Many methods can be applied to music and special effects. 13 November 2018 Veton Këpuska Architecture of a Respresentative 32 Bit Processor

Digital Systems: Hardware Organization and Design 11/13/2018 Applications (Project Areas) Speech Coding Goal is to reduce the information rate measured in bits per second while maintaining the quality of the original waveform. Waveform coders: Represent the speech waveform directly and do not rely on a speech production model. Operate in a high range of kbps Vocoders: Largely are speech model-based and rely on a small set of model parameters. Operate at the low bit range of kbps Lower quality then waveform coders. Hybrid coders: Partly waveform based and partly speech model-based Operate in the 4.8 – 16 kbps range 13 November 2018 Veton Këpuska Architecture of a Respresentative 32 Bit Processor

Digital Systems: Hardware Organization and Design 11/13/2018 Applications (Project Areas) Applications of speech coders include: Digital telephony over constrained bandwidth channels Cellular Satellite Voice over IP (Internet) Video phones Storage of Voice messages for computer voice mail applications. 13 November 2018 Veton Këpuska Architecture of a Respresentative 32 Bit Processor

Digital Systems: Hardware Organization and Design 11/13/2018 Applications (Project Areas) Speech Enhancement Goal is to improve the quality of degraded speech. Preprocess speech before is degraded: Increasing the broadcast range of transmitters constrained by a peak power transmission limits (e.g., AM radio and TV transmissions). Enhancing the speech waveform after it is degraded. Reduction of additive noise in (Digital) telephony Vehicle and aircraft communications Reduction of interfering backgrounds and speakers for the hearing impaired, Removal of unwanted convolutional channel distortion and reverberation Restoration of old phonograph recordings degraded by: Acoustic horns Impulse-like scratches from age and wear 13 November 2018 Veton Këpuska Architecture of a Respresentative 32 Bit Processor

Digital Systems: Hardware Organization and Design 11/13/2018 Applications (Project Areas) Speaker Recognition Speech signal processing exploits the variability of speech model parameters across speakers. Verifying a person’s identity (Biometrics) Voice identification in forensic investigation. Understanding of the speech model features that cue a person’s identity is also important in speech modification where model parameters can be transformed for the study of specific voice characteristics: Speech modification and speaker recognition can be developed synergistically. Speech (Voice) Recognition is covered in ECE 5526 Natural Language Understanding is covered in ECE 5527 13 November 2018 Veton Këpuska Architecture of a Respresentative 32 Bit Processor

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