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    • A11 3062 1 University of Pittsburgh Swanson School of Engineering March 7, 2013 DEVELOPMENTS IN VOICE REGONITION TECHNOLOGY Ronald Buttermore (rwb31@pitt.edu, 0012 Bon 6:00), Naseem Lee-Perkins (nrl28@pitt.edu, 0012 Budny 10:00) Abstract – Voice recognition software is “the process of taking the spoken word as an input to a computer program” [1]. Through this software, the goal is to be able to control a computer efficiently and intuitively [2]. Voice recognition, often only thought of as a way to command a cell phone, has many beneficial applications which can be expanded once improved to a more user friendly and accurate product. In this paper, the objectives will be to explain and analyze the importance of voice recognition and its applications through detail of research and development of and speech software, designs and implementations in current and future technologies, and existing problems with technologies and possible solutions. We will also detail the impact of voice recognition’s integration into engineering and society. Voice recognition software and its improvement, in ease of use and accuracy, could benefit the lives of many people, as the applications of the technology would increase. In addition, these applications have great potential with respect to sustainability and considering the needs of future generations along with meeting our own. These applications work towards benefiting the consumer and corporations alike. Voice recognition can allow users to go hands free and result in faster interactions. Companies that utilize the technologies may experience more productive workers, with higher output. Ultimately voice recognition creates a more appealing product which should generate new sales not only for companies making the software but also for companies using the software. To achieve our objective of displaying the importance of voice recognition technologies we will start by describing the process about how speech recognition works from a technical standpoint. We will be thoroughly outlining all pros and cons of the development of this software. Finally, we will analyze the impact of this technology on society. In conclusion, this paper will highlight the benefits of voice and speech recognition technologies by analyzing current products, how voice recognition works, and its societal and ethical impact. Key Words – Acoustic Model, HMM model, Language Model, Linguistic Interpretations, User Interface, Voice Recognition VOICE RECOGNITION SYSTEMS Voice recognition systems are electronic systems that help electronic devices respond to speech. Voice recognition systems have many uses but with current flaws voice recognition systems do not reach their full potential. This paper will focus on the critique of voice recognition systems and possible improvements to be made to the current software, which will increase the uses and benefits of the software. We will begin by explaining how voice recognition works. We will include hardware requirements and descriptions of different techniques used by different software to carry out these models. A description of multiple uses by many different individuals will be included to explain the importance and benefits of voice recognition software. These uses will prove the importance of voice recognition software and illustrate why flaws and the improvement of flaws are necessary. However, there are already proposed solutions for these flaws that will increase the effectiveness of the systems which will benefit many people. Recent developments in modeling speech through improving recognition models has helped voice recognition move forward. These recent improvements have opened up possibilities of new and reworked technologies that apply voice recognition software. These technologies have the potential to benefit and help progress society and its processes, specifically through the sustainable increase in quality of life. WHAT IS VOICE RECOGNITION AND HOW DOES IT WORK? A voice recognition system translates spoken word to digital signals that are processed to perform specific tasks. However, voice recognition systems have requirements for hardware and software in order to undergo this process. Requirements for Voice Recognition Software Basic voice recognition systems require 200 megahertz Pentium processor, a minimum of 64 megabytes of RAM, a basic microphone, and a minimum of a 16-bit sound card [2]. Although most voice recognition will run, improvements in these requirements can make a dramatic difference in the performance of the voice recognition software. Increasing the size of the RAM, processor, and sound card as well as investing in a better microphone can help in the improvement of the voice recognition system [2]. Along with these hardware requirements, voice recognition requires the use of software to collect, analyze, and interpret the data. Different software approaches this process in different ways. Acoustic and Language Models
    • Ronald Buttermore Naseem Lee-Perkins 2 The acoustic and language models are the basic processes in which sound is taken from the microphone and processed through the computer. In the acoustic model the voice is analyzed. After the user speaks into the microphone, background noise and unnecessary changes in volume are removed. Mathematical calculations are used to take the voice and convert it to a range of frequencies, which correspond to pitches in sound. The data is then analyzed and converted to digital representations of phonemes, which are the basic sounds of language [2]. Next, the language model analyzes the content of speech. The language model compares the combinations of phonemes to words in a dictionary, the database of the most common words in the English language. Dictionaries, or databases, of individual software may differ based on how each developer designs the language model process. Once the language model decides which word was spoken, the digital signal of the word is ready to be displayed or carry out its designated task [2]. While acoustic and language models are the basic ways voice recognition systems work, each system has a different way of approaching these systems. The design of software by each developer creates different techniques for voice recognition systems. Template Matching Template matching is a technique that uses user input and is referred to as a user dependent method. It has the highest accuracy, at 98%, but in turn has the most limitations [3]. Template matching starts with asking the user to speak several words or terms into a microphone. The words are repeated multiple times and a statistical average of the sample words is stored used as a template [3]. Other programs may come already loaded with digital voice sample templates. Once the user speaks into the microphone the electrical signal is converted to a digital signal using an analog to digital converter and is stored in the memory. The analog to digital converter takes a physical quantity and converts it to a digital number [2]. Digital signals are compared to those of the templates, and meaning is deduced producing a word [3]. Some software also uses pre- programed rules to help find meaning [4]. Feature Analysis Feature Analysis is the speaker independent technique of voice recognition software. It processes voice input using Fourier Transforms or Linear Predictive Coding. Fourier Transforms make a “generic function”, based on a quantity like time, and convert it to another function based on a physical property like frequency [5]. Fragniere, van Schaik, and Vittoz describe the objective of Linear Predictive Coding as a way “to predict the current value of the signal using a linear combination of previous samples, each weighted by a coefficient [6].” These two processes mimic digital signals of real voice and the software attempts to find characteristic similarities between expected inputs and actual digitized voice input [3]. The similarities produce results that correspond to a word. These similarities are present for a wide range of speakers, so no user training is required. Once a more efficient speaker independent software, like feature analysis, is developed the system would be able to account for accents, speed of delivery, pitch, volume, and inflection [3]. THE APPLICATIONS AND IMPORTANCE OF VOICE RECOGNITION SOFTWARE Voice recognition can have many applications, which can benefit the lives of many people. Uses of voice recognition software include learning tools, corporate and consumer uses, helping people with disabilities, and government use. Learning Uses and Benefits Learning can also be benefited by the use of voice recognition software. It can be used to improve a user’s first language addressing issues like pronunciation which can be affected by ethnicity, social class, and education [7]. Because voice recognition systems are often looking for traditional pronunciation of a word, error messages can alert users to incorrect pronunciation. With repeated use of voice recognition software along with error messages, users can learn and practice to correctly pronounce words. A similar idea can help users learn a second language as software can be programed to mimic accents of other languages [7]. Again with practice and error analysis, voice recognition software can shape a user’s pronunciation and delivery of a non-native language. Voice recognition can also be used to help individuals with learning disabilities like dyslexia, as it allows them to easily use a computer and encourages writing [8]. Voice recognition software can help improve the education level of many individuals through helping with speech problems and learning disorders, and as a tool to teach a second language. Also through aiding the learning process of a second language, voice recognition systems help break down cultural barriers, letting users connect with people without a language barrier. This is an increasingly important aspect of education as the world becomes more and more diverse and it is important to be able to communicate and connect with people from different areas of the world. The importance of education and learning is a basic need that could be improved by voice recognition technology, which would also potentially improve the quality of life for many people.
    • Ronald Buttermore Naseem Lee-Perkins 3 Consumer Uses and Benefits Voice recognition software can be utilized by the everyday consumer. Consumers can use voice recognition software to dictate emails, navigate applications on electrical devices, create documents, and search the web [9]. Voice recognition systems also help people with disabilities. People with speech disorders and people who are deaf or hard of hearing can benefit from voice recognition software [10]. Voice recognition systems can help facilitate faster interactions between the deaf or hard of hearing with others, especially those who do not know sign language, as speech can be displayed as it is spoken. Voice recognition systems can also help people with motor problems, physical disabilities, and learning disabilities because would allow them to use electronic devices without having to use their hands [8]. Voice recognition allows for hands free use of computers and electric devices. This allows for faster interactions with electric devices as options are no longer limited to screen size and there is no need to thumb through pages of options. Voice recognition also saves the consumer time when typing is involved because words can often be dictated faster than they can be typed. With new laws that require drivers to use electronic devices hands free, voice recognition systems are now more useful in phones and other devices. The ability to control these devices without the use of hands makes roads safer for drivers and pedestrians. With safer roads, increased productivity, and aid towards the disabled, voice recognition software has obvious benefits towards the improvement of quality of life. Corporate Uses and Benefits Many different professions can use voice recognition systems to help improve productivity. Voice recognition can help reporting, healthcare systems, and call centers. Healthcare systems often use vice recognition software as a way to quickly enter electronic health records [11]. Call centers allows users to participate in different activities or transactions without waiting to talk to a live representative. Careers in reporting often require quick typing; however with the use of voice recognition systems words can be more easily recorded and processed. The main benefit of voice recognition software for companies is increased productivity. In healthcare, workers can enter information faster. Call centers don’t have to be flooded with calls, as computers can process human input and deliver results, freeing up workers to complete other tasks. Reporters no longer have to worry about quick typing and shortening words, with the risk of error and later misunderstanding, as speech can be recorded and processed as it is spoken. Implementing voice recognition software into companies can thus improve a company’s productivity. Government Uses and Benefits Voice recognition software can be implemented to help the government. Many different government agencies use voice recognition including law enforcement, legal departments, and case working [6]. These agencies may use voice recognition software in much of the way that corporate companies do. Employees can write quicker, easily and quickly search documents, and quickly navigate the internet and computers. However, the government can also use voice recognition software in the military. The most common use of voice recognition software in the military is in “command and control” which allows a control of a device or a system through spoken commands. The military also uses voice recognition software for speaker detection, and speaker verification [12]. This allows the military to detect when someone is speaking and confirm the identity of that person. Government agencies similar to companies also experience some of the same benefits as they also experience increased productivity. However, since government agencies tend to deal with more important matters, the productivity experience is more beneficial to the public. Military uses of voice recognition present the public with benefits in safety since voice recognition systems can improve and aid operations. Implementing voice recognition systems in “command and control” help keep soldiers safe, as they no longer are required to enter some of the dangerous situations where some of the control devices must go. However, uses and benefits of voice recognition system are currently limited because of design flaws in the certain software, which process the voice input and analyzes it, and hardware, which have yet to make full use of voice recognition technology. CURRENT FLAWS AND LIMITATIONS While voice recognition software does work, there are some flaws and limitations to the current software that can be improved in order to make the systems more user-friendly and effective. One of the current flaws in some of the voice recognition software is the use of word systems. Most word systems are discrete or connected. This means they can only process one word or short phrases, respectively. This system requires users to use clear articulate speech, making sure not to slur their words. Users must be especially careful not to slur the ends of their words in connected word systems where it is easy to slur the end of one word into the beginning of the other [3]. This creates a problem with users as speech becomes unnatural. These words systems present problems for some uses of voice recognition software. One example of this issue is in reporting where voice recognition software is needed to rapidly record speech. However, speech may not always be correctly pronounced or clearly articulated. While the discrete and connected word systems are the easiest to
    • Ronald Buttermore Naseem Lee-Perkins 4 implement, there is a third type of word system that can be used, the continuous speech system. Unfortunately continuous speech systems are the hardest to implement. Another problem with voice recognition systems is homophones [2]. Homophones, words that sound the same but have different meaning, are difficult to distinguish in voice recognition systems. Because voice recognition systems match the patterns of the sounds of phonemes with words in a dictionary, homophones present multiple choices in the system and the correct word is not always selected. While some voice recognition systems use statistical models to select the most probable word, this does not always present the correct word. Other systems attempt to use trigrams, which analyze the context to decide which word to use. However, if the system is also operating with a discrete word system, which is only a single word, there isn’t any context to help analyze the meaning of the word. User dependent systems also present multiple problems for voice recognition systems [2]. Because user dependent systems need to be adjusted by the user in order to become familiar with an accent or speech pattern, they are not practical for widespread use. This presents problems for professional uses like reporting or call-centers, where a wide range of accents, dialects, and speech patterns need to be understood. Not only would the flaws keep companies from effectively completing tasks but in cases like a call center, where there is client interaction, clients may grow frustrated with the process and company. These flaws can also hinder learning efforts and keep individuals with disabilities from easily using electronic devices which could be detrimental in a world which is becoming more reliant on electrical devices. IMPROVEMENT SOLUTIONS Overcoming Flaws The flaws discussed above provide software and hardware developers a challenge to overcome language interpretation barriers such as speech variations among different users, innate language problems like homophones, and user dependent systems. These problems are being worked on by companies and individuals in order to optimize the efficiency and accuracy of voice recognition systems and improve technologies that are beneficial in various practical applications. Solutions that are currently being developed and implemented are software designs such as the Neural Network Algorithm, Hidden Markov Model, the MFCC algorithm, and combinations of multiple models and algorithms. These solutions have beneficial applications in areas such as security, convenience and accessibility for the handicapped, emotion recognition, aiding scientific research, and performing everyday tasks. Modeling Speech While speech recognition rates are low compared to a technology like image recognition, research and development of this software has of late grown steadily due to growing expectations. The main challenge in designing voice recognition software is not only analyzing frequency and change in frequency of the voice, but also to attempt to replicate with an algorithm how the brain recognizes phonemes and syllables in speech. Two different main models have been proposed and studied in order to extract the speech signals from a voice and analyze their feature parameters to have the computer recognize the speech input. One model is based on a probabilistic approach algorithm, while the other is an analytical algorithm. The Neural Network (NN) recognition algorithm, mainly analytical, uses a large coefficient matrix to match feature parameters of syllables and words to an output index. This is not very efficient. However, since every individual speech signal must be run through the algorithm in order to be matched, the algorithm must start from the beginning with every new speech input. This is not ideal because of its slow rate of recognition. A more probabilistic approach such as the Hidden Markov Model (HMM) has proven to be faster with recognition when faced with a larger number of speech samples. The HMM attempts to improve recognition rates by overcoming challenges such as rate of speech, ambient noise, and varying voices by more successfully extracting unique feature parameters of audio signals generated by the voice [13]. Hidden Markov Model The Hidden Markov Model selects quantitative parameters in order to identify the unique features of speech. An algorithm named the Mel-Frequency Cepstral Coefficients (MFCC) algorithm is most commonly used to identify specific parameters from a voice signal, which the HMM uses to isolate further parameters. The MFCC is a way of representing sound as a cepstrum (power spectrum on a non-linear mel scale of frequency) by transforming the cepstrum into a coefficient matrix. The matrix is a representation of the syllable or word, which the HMM uses to match to an initial database using various matrix transformations to analyze based on a sequential probabilistic model. As new voice and speech inputs are transformed into MFCC matrices for different speakers and syllables/words and inputted into the HMM, the HMM’s initial probability is changed due to the variation of these conditions. This transition probability is combined with the initial probability based on the difference in number of states and events in both transformations of MFCC matrices to form a resulting observational probability. The three probabilities (initial, transition, and observation) are then used as variables to compare a test word or phrase to a pre- trained test word or phrase. Improvements on these three
    • Ronald Buttermore Naseem Lee-Perkins 5 variables are taken into account by the HMM when comparing inputs. Applications of the HMM have been tested, and research has found that when the number of sample inputs increases, the recognition rate increases, proving the HMM model to be successively more accurate. A Mel-frequency index increase also slightly increases accuracy, but slows processing time [13]. HMM ALGORITHM RECOGNITION RATE [13] The rate of recognition of the HMM algorithm based on various factors MFCC Improvements While the HMM focuses on interpreting user speech as language, a solution that attempts to more accurately recognize the speaker’s identity is a robust computer voice recognition improvement of the MFCC algorithm based on an individual user. This improvement tests a user’s voice patterns and utilizes an improved MFCC algorithm to produce a faster, more accurate result for voice recognition. It attempts to achieve text-independent speaker identification, or the identification of a user by their voice without regards to the user’s specific language or words. The modifications to the original MFCC include slightly changing steps of the MFCC algorithm that convert the sound into a MFCC matrix. After the speech signal is first blocked into frames, it is windowed in order to minimize error in signal discontinuities. Using the function of a Kaiser window instead of a traditional Hamming window is an improvement in that it minimizes the mean square error instead of maximum error. A Fast Fourier Transformation is used to convert the windowed frames from a time domain to a frequency domain, which is then filtered using a Mel-scale, which attempts to emulate the way the brain processes different frequencies of speech as non-linear. Modifying the way the Fast Fourier Transformation is applied over a Mel filter has shown to reduce computing costs and make the algorithm more efficient. Another suggested feature matching technique (similar to HMM) is called Vector Quantization. In this method, vectors assigned to MFCC are mapped to a large area of space instead of matrices used in HMM. Each small region within is referred to as a cluster, with multiple centers of clusters (codewords) comprising a codebook. To feature match, input MFCC vectors are compared to clustered MFCC initial training vectors. Research has shown these modifications to the MFCC technique increase the speed of the algorithm (from 0.12 ms to 0.11 ms) and increase the accuracy (from 66% to 80%) in a sample of 50 tests [14]. Combining Methods Various methods to obtain faster, more accurate speech recognition, such as the ones previously detailed, all have their own strengths and weaknesses. A solution proposed in order to eliminate weaknesses in different approaches to improving voice recognition and interpretation is to combine multiple methods. One of these combinations is using the HMM with Prediction by Partial Matching (PPM) method. PPM is a technique that uses statistical analysis based on context to predict the next character in a series. When combined, a new system is created that uses the voice and word recognition strengths of HMM with the prediction matching of PPM to greatly improve input processing and recognition [15]. Combinations of multiple proposed solutions could be the key to the goal of increasingly accurate voice recognition. BENEFITS OF IMPROVEMING VOICE RECOGNITION SYSTEMS Practical Applications Improved voice recognition technology is a further step towards beneficial applications of the software in many fields and aspects of life. These aspects can be applied in consumer, corporate, industrial, and scientific fields in various ways such as security, automation systems, ease of use increases (convenience), and aiding other voice based tasks. As the reliability and integration of this technology increases, the more practical uses we will find will also increase. Security One of the benefits provided by the improvement of voice recognition software is the major application it has in security. The potential for vocal based security systems gives an added layer of protection in an era of information. Speech recognition makes it possible to verify a person’s identity through voice interfaces such as the phone and computer microphone. This gives a person access to various control and security actions such as controlling a mobile device, voice banking, voice mail, voice activated security control over certain devices, and remote access to a computer [14]. Biological means of controlling computer systems helps prevent fraud and theft based on an individual’s unique physical characteristics [15]. Ease of Use and Handicap Accessibility
    • Ronald Buttermore Naseem Lee-Perkins 6 Another of the various benefits of the applications of voice recognition systems is the increase in ease of use for controlling computer systems. This is probably one of the most useful applications of the voice recognition software, as it provides a means of control based on one of a person’s most basic and instinctual processes: speech. Not only does this make communication and control easier, it also gives people with less access to controlling computers and even basic machines a way to avoid having to physically control systems. A home automation system was developed in order to assist handicapped persons and the elderly with basic household tasks they may be incapable of doing themselves. Combining speech recognition software with wireless networks allows the user to control most electronic devices by voice, providing a 79.8% accuracy with 1225 commands [16]. Sustainability: Looking Forward As our use of technology grows and advances, more and more emphasis is being placed on the sustainability of our current systems and lifestyles, whether it is environmental or societal. There is a growing awareness of the challenges we must overcome in order to be able to sustain equilibrium between meeting our present needs and ensuring that we leave behind a world where future generations can live comfortably. While a discussion of environmental impact with regards to computer technologies and software would be less meaningful than most other engineering topics, voice recognition technology presents advantages that offer flexibility in sustaining and improving quality of life. As voice recognition technologies improve and unfold into new applications, it is definitely a tool that could be used on quality of life and sustainability enhancements. Sustainability with regards to quality of life upgrades is an important factor to consider when weighing the importance of a technology such as voice recognition software. Voice recognition software provides clear improvements to quality of life. One example is the direct applications to people with disabilities. Certain functionalities of the technologies involved would provide disabled people to become more independent. Less reliance on other people creates a more enjoyable, free experience where the disabled can find more meaningful interactions and come closer to living a normal lifestyle. Even for normal people in a home or work environment, less work and effort has shown to reduce stress, increasing quality of life where voice recognition technology cuts down on manual labor. Along with creating more significant experiences for people due to its simplistic and intuitive nature, voice recognition technology could also help improve quality of life through its applications relevant to making the world a safer place. Governments will have a better way to operate smoothly and protect its citizens, through voice verification systems and secure identity techniques. Even smaller impacts such as hands-free control of a mobile device in a motor vehicle could help reduce accidents and create safer roads. The elimination of distractions due to the ability to control electronics vocally would make the world safer and improve quality of life. CONCLUSION: FUTURE DEVELOPMENTS OF VOICE RECOGNITION SYSTEMS In conclusion, voice recognition software, its improvements, and technological applications have the potential to positively affect the future of human society. Its useful applications in security, productivity, and efficiency provide concrete reasons why the development, improvement, and integration of this technology is so important. From consumer uses to government uses, voice recognition is an important technology that has the potential to benefit the lives of many people, and sustainably improve the quality of life for future generations. REFERENCES [1] (2009, April 30) .“Voice Recognition Systems”. US Food and Drug Administration. http://www.fda.gov/ICECI/Inspections/InspectionGuides/Ins pectionTechnicalGuides/ucm093579.htm [2] S. Miastkowsk. (2000, April 14). “How It Works: Speech Recognition.” PC World. (Online Article). http://www.pcworld.com/article/16276/article.html [3] J. Baumann. “Voice Recognition.” Human Interface Technology Lab. (Online Article). http://www.hitl.washington.edu/scivw/EVE/index.html [4] D. Borghino. (2012, August 24). “New approach promises more accurate speech recognition software.” Gizmag. (Online Article). http://www.gizmag.com/speech- recognition-ntnu/23870/ [5] T. Tao. “Fourier Transforms” Department of Mathematics, UCLA. http://www.math.ucla.edu/~tao/preprints/fourier.pdf [6] E. Fragniere, A. van Schaik, E. Vittoz. “Linear Predictive Coding of Speech Using an Analogue Cochlear Model”. Swiss Federal Institute of Technology. (Online Article). http://goo.gl/sA5nB. [7] A. Neri, C. Cucchiarini, W. Strik. “Automatic Speech Recognition for Second Language Learning: How and Why it Actually Works”. Department of Language and Speech, University of Nijmegen. (Online Article). http://goo.gl/XiN80. [8] “Speech Recognition For Learning”. Brainline.org. (Online Article). http://www.brainline.org/content/2010/12/speech- recognition-for-learning_pageall.html [9] (2008 August). “Dragon NaturallySpeaking Professional for Government”. Nuance Communications. (Online
    • Ronald Buttermore Naseem Lee-Perkins 7 Article). http://www.nuance.com/ucmprod/groups/dragon/documents/ webasset/nd_004913.pdf [10] R. Hoyt (2010 January 1). “Lessons Learned from Implementation of Voice Recognition for Documentation in the Military Electronic Health Record System”. National center for Biotechnology Information. (Online Article). http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2805557/ [11] (2005 December).“Use of Speech and Language Technology in Military Environments”. NATO Research and Technology Organisation. (Online Article). http://www.stephanepigeon.com/Docs/TR-IST-037-ALL.pdf [14] S. Jarng. (2011). “HMM Voice Recognition Algorithm Coding” IEEE. (Online Article). http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5 772321 [15] C. Leon. (2009). “Robust Computer Voice Recognition Using Improved MFCC Algorithm” IEEE. (Online Article). http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5 260824 [16] B. Wang, J. Zhang. (2010). “A novel voice recognition model based on HMM and fuzzy PPM” IEEE. (Online Article). http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5 656855 ADDITIONAL SOURCES AlShu’eili, H. "Voice Recognition Based Wireless Home Automation System." IEEE Xplore. IEEE, 2011. Web. <http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=>. Aziz, A. "Security System Using Biometric Technology: Design and Implementation of Voice Recognition System (VRS)." IEEE Xplore. IEEE, 2008. Web. <http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=>. ACKNOWLEDGMENTS Thanks go to the Swanson School of Engineering, the engineering professors and writing instructors, the library, coffee, and the Internet.