Browsing by Author "Dolawattha, D.D.M."

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An analysis of sound parameters for prosodic modeling in Sinhala text to speech synthesis
(Research Symposium 2009 - Faculty of Graduate Studies, University of Kelaniya, 2009) Dias, N.G.J.; Kumara, K.H.; Dolawattha, D.D.M.
Speech synthesis is the artificial production of human speech. A computer system used for this purpose is called a speech synthesizer, and can be implemented in software and/or hardware. Text-to-Speech (TTS) is one of the speech synthesis technologies. Before a synthesizer can produce an utterance, several steps have to be completed. Among them, after computing the basic pronunciation from authographic text, prosody annotation should be performed. Finding correct intonation, stress, and duration from written text is the most challenging problem for most of the natural languages. These features together are called prosodic or suprasegmental features and may be considered as the melody, rhythm, and emphasis of the speech at the perceptual level. Unfortunately, written text usually contains very little information of these features and some of them change dynamically during speech. However, with some specific control characters this information must be given (at least some extend) to the speech synthesizer to produce enough natural speech of the target language. On the other hand timing at sentence level or grouping of words into phrases correctly is difficult; in many languages, prosodic phrasing is not always marked in text by punctuation, and phrasal accentuation is almost never marked. If there is no breath pauses in speech or if they are in wrong places, the speech may sound very unnatural or even the meaning of the sentence may be misunderstood. As an example, in Sinhala, the input string " wïu wdjo@ ” " can be spoken as three different ways changing the intonation patterns as angry, sadness and sarcastic; giving three different meanings to the listener. Here intonation means how the pitch pattern or fundamental frequency changes during speech. The prosody of continuous speech depends on many separate aspects, it may be twice as high as with male voice and with children it may be even three, such as the meaning of the sentence and the speaker characteristics and emotions. Therefore it is clear that prosody plays a major role in speech synthesis, and a deeper treatment of prosody is a must in any kind of speech synthesis. In this work, in order to develop generic models for prosodic synthesis in speech synthesis, we selected 150 possible sentences in Sinhala Language and recorded them according to the above three intonation patterns (i.e. angry, sadness and sarcastic) with a female native speaker who is a well trained person in Drama and Theater. Then we computed various speech parameters for above 150X3 sentences using PRAAT speech processing tool developed by www.praat.org. Hence we found that for all above 150 sentences there is an incremental pattern in the duration from Angry to Sarcastic. No regular pattern in Median, Mean, Standard Deviation, Minimum, and Maximum values of the Pitch parameter. Regarding the pulses, we computed the Number of pulses, Number of periods, Mean period, Standard deviation of period for each of the above sound files and we observed that there is no regular pattern in the parameter Pulses. For voicing parameter we computed the Fraction of locally unvoiced frames, Number of voice breaks and Degree of voice breaks. However for this parameter there were not regular patterns too. Then we computed the Harmonicity values as Mean autocorrelation, Mean noise-to-harmonics ratio, Mean harmonics-to-noise ratio and found that there is no regular pattern. After computing the mean-energy intensity of each sentences, we found that there is an incremental pattern in the Intensity by concerning the order Angry, Sarcastic and Sadness. Finally we computed the formant values as First formant, First Bandwidth, Second Formant, Second Bandwidth, Third formant, Third Bandwidth, fourth formant and forth bandwidth and found that there is no regular pattern in different formant parameters. Although there are no regular patterns in most of the above speech parameters, in order to develop a more natural sounding speech synthesizer, however these parameters should be annotated with basic pronunciation computed from the authograpich text in speech synthesis. Therefore in future we hope to develop more generic probabilistic models based on this analysis to model above speech parameters for Sinhala speech synthesis.
Classification and Regression Trees (CART) based Data Driven Approach for Prosody Duration Modeling in Sinhala Language
(Research Symposium 2010 - Faculty of Graduate Studies, University of Kelaniya, 2010) Dolawattha, D.D.M.; Dias, N.G.J.; Kumara, K.H.
A Text-to-Speech (TTS) Synthesizer or Text-to-Speech Engine is a computer based system that capable to read any text aloud with naturally. In TTS, the text might be inserted directly to the computer by an operator or an output file of an Optical Character Recognition (OCR) system of a scanned written text document. Prosody features play a major role when developing a TTS system. Getting the correct intonation, Stress and duration from written text is the most challenging problems for natural languages. The prosodic duration highly affect on machine generated synthetic speech’s naturalness and intelligibility. Here we have used different features that are automatically derived from the text and affect on the duration pattern of the natural speech to be modeled the duration. In this work, in order to develop generic models for prosodic synthesis in speech synthesis, we have selected a speech corpus of 150 possible sentences in Sinhala Language and recorded them according to the three intonation patterns angry, sadness and sarcastic with a female native speaker who is a well trained person in Drama and Theater. Both the waveform and the spectrogram were used to determine the segment (phoneme) boundaries, and the boundaries identified are confirmed by listening to the speech. Each segment in the corpora was annotated with the following features together with the actual segment duration and finally generated the CART. Identity of the current phoneme, Identity of the preceding phoneme, the features considered are the Identity of the following phoneme, Position in the parent syllable, Parent syllable initial, Parent syllable final, Parent syllable position type, Number of syllables in the parent word, Position of parent syllable in the word, Parent syllables break information, Phrase length (number of words) and Position of phrase in the utterance. Above features were observed from similar worked carried out for other languages specially Asian languages [1]. Predictions of the segmental durations were done as follows. The decision tree (CART) was traversable starting from the root node, taking various paths satisfying the conditions at intermediate nodes, till the leaf node is reached. The leaf node contains the value of segmental duration prediction.
Designing and implementation of new computer software system for the Centre for Open and Distance Learning
(Research Symposium 2009 - Faculty of Graduate Studies, University of Kelaniya, 2009) Dias, N.G.J.; Dolawattha, D.D.M.
Nearly 150000 students were qualifying for university education in Sri Lanka annually. But only 18000 students are selected to follow different undergraduate courses in local universities where we have free education. Remaining students have to follow external degree programmes conducted by National universities, professional courses conducted by private sector institutes or Government institutes and few are going abroad for higher education. Large portion of students are registered annually at the University of Kelaniya among the students who follows external degree courses at different national universities. Nearly 85500 students were registered from 1993 to 2008 and 13716 students were graduated from them so far. We have identified that after the year 2005 more than 10000 students are registering annually. Five different degree courses are offered and 16 exams and 16 seminars need to be conducted for them annually by the CODL. We require more robust, powerful, user friendly and reliable Computer Software System (CSS) by considering rapidly growing students capacity and services rendered to them. On the other hand we require a CSS, because a new exam evaluation system (NEES) has been introduced from the student batch 2007. In that NEES offered course units with particular credit value and each student needs to be completed specified no of credits within a specified period of time relevant to the degree followed. CSS is a Management information System (MIS) type Multi-user Computer System working in a local network environment and password restricted users will be operated the system. Main functionalities will be student registration, conducting exams, printing admissions, printing transcripts and certificates and other required sub functionalities come under above. All functional requirements, non-functional requirements and domain requirements were identified. System was designed by integrating concurrency control and user authorization. The authorized users will only be the CODL Staff and categorize them according to their job assigned. (i.e. Student registration user, Examination data entry user etc.). User authorization subsystem considers different functionalities of the CSS and gives access to each user category by considering their job assigned. Limitations and constraints have to be considered when developing the CSS. It will not be connected to the Campus wide network and run in a separate server with a view to avoid internet hacking and reduce the internet virus risk. Examination results are being published on the CODL web, which runs in a separate server. Storing data in the database is unlimited and the database backup facility is an important feature. Potential usefulness of the CSS are the Maintainability and Modularity. An Integrated software process model was used to model the CSS between two software process models, Incremental development and Rapid application development. More user friendly and interactively interfaces will be developed in CSS. Designing the CSS is done using Rational Rose with object oriented software design techniques. It was developed on .Net framework using VB.Net as the front-end tool and SQL Server as the back-end tool.
The Influence on Mobile Learning: Mobile Learning Contents, Higher Education Institutes, and Communication Technology
(IEEE, 2020) Dolawattha, D.D.M.
In the present era, mobile learning has secured a better position in modern technology base learning paradigms. It surpasses other conventional learning methods because of ubiquity, mobility, attractive content, facilitated connectivity, and institutional engagements. The main objective of this study is to identify how mobile learning content, higher education institute, and communication technology factors influence learners and tcachers when using sustainable mobile learning in higher education. Through the literature reviewn we developed three separate impact models i,e. mobile learning content, higher education institute, and communication technology with separate impact factors. We used pre and post usage survey questionnaires of60 tea0hers and 60 learners to evaluate these models. Primarily, they were asked to fill the pre-usage questionnaire with their initial mobile learning experience. Then, they were allowed to use the modified Moodle mobile app and asked to fill the post-usage questionnaire. The results reveal that the most significant influencing factors are, ease of use in mobile learning content, and facilitating conditions for higher education institutes and communication technology models. Finally, we can conclude that users prefer to have easy to use mobile learning content with better service facilities in higher education institutes and communication technologies.
Modelling the Learner’s Perspectives on Mobile Learning in Higher Education
(University of Colombo School of Computing, 2018) Dolawattha, D.D.M.
Mobile learning is a novel learning technique prevailing in the modern world. It has been identified that the important and balanced contribution from different stakeholders are required to create an environment for a better mobile learning experience. There are many reasons for learners to select mobile learning as an environment for their academic activities. The main objective of this study is modelling the learner influencing factors on mobile learning adoption for their learning activities in applicable and sustainable manner. The six main adoption factors are identified for the proposed model namely usefulness, interactivity, motivation, attitude, facilitating conditions, and ease of use. In the evaluation process, online pre-usage and post-usage questionnaires were used to introduce above six factors and 150 undergraduate students were obtained as a sample. Initially, the students were asked to fill the pre-usage questionnaire and secondly, they were obtained in the novel mobile learning system by using its features and facilities and finally, asked to fill the post-usage questionnaire. Results of the present study reveals that the most significant influencing factor is “Interactivity” on the learner’s mobile learning adoption. In conclusion, incorporating interactivity, usefulness, motivation, attitude, facilitating conditions and ease of use into the mobile learning adoption can better explain the learner perspectives in applicable and sustainable mobile learning framework
Shifting teachers’ insights towards utilizing mobile based learning technologies in covid 19 pandemic situation
(Faculty of Graduate Studies - University of Kelaniya, Sri Lanka, 2021) Dolawattha, D.D.M.; Premadasa, H. K. Salinda
It is very important to change the way of pursuing learning activities since the learning environment is changing every day due to various reasons such as advancement of the technology, health concerns such as present COVID pandemic situations, etc. For these reasons, one of the prevailing possibilities to change the method of academic service delivery is the use of mobile-based learning technologies. It is interesting to discuss that how teachers absorb mobile-based learning technologies when their academic services are disseminated. The main objective of this study is to identify the influencing factors for teachers to adopt mobile-based learning sources such as mobile learning applications, learning web portals, gamification, augmented reality, Learning tools (Chat, forums, assignments, quizzes, video, etc.), digital libraries, and learning management systems (LMS) in primary, secondary, and higher education. The study uses quantitative research methodology by utilizing data collected through an online survey questionnaire to understand the most significant factors for teachers’ perception to opt for mobile-based learning technologies. The sample of the study consists of 75 primary and secondary teaches who work in local schools and higher education institutes in Sri Lanka. The proposed impact model for teachers’ insight to utilize mobile-based technologies in education under COVID 19 pandemic situation, consists of six impact factors such as interactivity, usefulness, ease of use, facilitating conditions, ICT self-efficacy, and ICT Anxiety. The questionnaire includes six questions developed based on the proposed impact model. The five-point Likert scale values one to five for strongly disagree to strongly agree was used in the questionnaire to convert user responses and do statistical analysis. The statistical analysis was done using the Pearson correlation coefficient test to test the hypothesis and calculate the correlations among impact factors in the proposed model. The MINITAB computer application for windows was used to carry out the statistical calculations. According to the study results, correlations of each observed variable of the proposed impact models were greater than 0.5 and closer to 1. Therefore, each impact factor in the proposed model is strongly connected with the latent variable “teachers’ insight to utilize mobile-based technologies in education under COVID 19 pandemic situation”. This denotes that the teachers’ insight to utilize mobile-based technologies in education under the COVID 19 pandemic situation depends on mobile-based technologies’ integrated qualities such as interactivity, usefulness, ease of use, and facilities available, and also teachers’ ICT self-efficacy, and ICT Anxiety. However, according to the study results, the most significant factor for teachers’ mobile-based technology usage is ‘Facilitating Condition’. Finally, it can be concluded that the teachers are influenced by the facilities available in the mobile-based learning technologies. And they have realized the appropriateness of mobile-based learning technologies for learning in COVID pandemic situations especially in quarantined isolations and lockdown restrictions.