Dr. T. Nagarajan

Professor & Head of the Department

Dr. T. Nagarajan Ph.D

Email: nagarajant@ssn.edu.in

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Dr. T. Nagarajan earned his PhD degree from the Computer Science and Engineering department of IIT Madras in the year 2004. In his doctoral research, he was working on spoken language identification task. After his PhD, he joined TeNet group of IITM as a Senior-project-officer. During this period he was working on a project, named, Multimodal Interface. Subsequently, he joined the National Institute of Scientific Research (INRS), Montreal, Canada, as a postdoctoral fellow and worked there for two years. During his postdoctoral research he was focusing on Continuous speech recognition task, in which he specifically focused on discriminative training techniques for better classification.

After two years of postdoctoral research, he has joined SSN College of Engineering as a professor and he has been serving SSN since then. He has around 21 years of teaching experience. In addition to teaching, he has 7 years of pure-research experience both in India and abroad. Presently, he is a recognized supervisor of Anna University, Chennai, supervising two full-time Ph.D scholars, and has supervised two full-time and two part-time PhD scholars, in the area of speech signal processing, speech synthesis and speaker recognition. He received the Chief Minister’s Award for Tamil Computing for the year 2018, from the government of Tamil Nadu,for his contribution to Tamil for building a lightweight HMM-Based speech synthesizer and devloping various applications.

Dr. T. Nagarajan’s areas of research include speech signal processing, continuous speech recognition, statistical parametric speech synthesis, speaker verification/identification, spoken language identification, segmentation of speech into subword units. He has published more than 100 research papers in his area of research both in international journals and conference proceedings.

Project details:

  • Title: Tamil Pronunciation Error Detection Aid for Children – Prototype
    Funding Agency: Murasu Systems Sdn Bhd, Malaysia
    Chief Investigator: Dr. T. Nagarajan
    Co-Investigator: Dr. P. Vijayalakshmi
    Status: Completed
    Duration: Sep 2019 – Sep 2019
    Amount: Rs. 0.5 lakh
  • Title: IndiBol: Conversational Speech Platform for Tamil Language
    Funding Agency: Department of Information Technology, Govt. of India
    Chief Investigator: Dr. T. Nagarajan
    Co-Investigator: Dr. P. Vijayalakshmi
    Status: Proposal Submitted
    Duration: 2020 – 2023
  • Title: Speech Assistive Aids for Visually-Challenged People
    Funding Agency: Tamil Virtual Academy (TVA), Chennai
    Chief Investigator: Dr. T. Nagarajan
    Co-Investigator: Dr. P. Vijayalakshmi
    Status: Completed
    Duration: Aug 2018 – Aug 2019
    Amount: Rs. 25 lakhs
  • Title: Speech-Input Speech-Output Communication Aid (SISOCA) for Speakers with Cerebral Palsy
    Funding Agency: DST-TIDE
    Chief Investigator: Dr. P. Vijayalakshmi
    Co-Investigator: Dr. T. Nagarajan
    Status: Ongoing
    Duration: May 2017 – Apr 2020
    Amount: Rs. 13.72 lakh
  • Title: HMM-based Text-to-Speech Synthesis System for Malaysian Tamil
    Funding Agency: Murasu Systems Sdn Bhd, Malaysia
    Chief Investigator: Dr. T. Nagarajan
    Co-Investigator: Dr. P. Vijayalakshmi
    Status: Completed
    Duration: Nov 2016 – Jul 2017
    Amount: Rs. 4 lakh
  • Title: Speech-Enabled Interactive Enquiry System in Tamil
    Funding Agency: Tamil Virtual Academy (TVA), Chennai
    Chief Investigator: Dr. T. Nagarajan
    Co-Investigators: Dr. P. Vijayalakshmi, Dr. B. Bharathi, Ms. S. Sasirekha
    Status: Completed
    Duration: Mar 2016 – July 2017
    Amount: Rs. 9.52 lakh
  • Title: Development of Text-to-Speech System in Indian Languages: High-Quality Text-to-Speech Synthesis and Small Footprint TTS Integrated with Disability Aids (A consortium project with IIT Madras as Team Leader)
    Funding Agency: Ministry of Electronics and Information Technology (MeitY), Government of India, New Delhi
    Chief Investigator at SSNCE: Dr. T. Nagarajan
    Co-Investigators at SSNCE: Dr. P. Vijayalakshmi and Dr. A. Shahina
    Status: Completed
    Duration: 2012 – 2017
    Amount: Rs.77 lakh
  • Title: An assessment and intelligibility modification system for dysarthric speakers
    Funding Agency: AICTE – RPS (A), New Delhi
    Investigators: Dr. P. Vijayalakshmi and Dr. T. Nagarajan
    Status: Completed
    Duration: 2010 – 2012
    Amount: Rs. 9 lakh
  • Title: Design of lab model of speech processor for cochlear implants
    Funding Agency: SSN Trust
    Investigators: Dr. P. Vijayalakshmi, Dr. T. Nagarajan& Dr. A. Shahina
    Status: Completed
    Duration: 2010 – 2012
    Amount: Rs. 0.8 lakh
  • Title: Anatomical vibration sensor speech corpus for speech applications in noisy environments.
    Funding Agency: SSN Trust
    Investigators: Dr. A. Shahina, Dr. T. Nagarajan& Dr. P. Vijayalakshmi
    Status: Completed
    Duration: 2010 – 2012
    Amount: Rs. 1.23 lakh

Publications:
Patent filed:

  • P.Vijayalakshmi, T. Nagarajan and T.A. MariyaCelin have filed a patent titled “A Speech-input Speech-output Communication Aid for Speakers with Cerebral Palsy” in the Indian Patent office on 02.08.2019.  (Reference number: 201941031287)

Book chapters:

  • P. Vijayalakshmi, T. Nagarajan, “Assessment and intelligibility modification for dysarthric speakers”, Chapter 3 – Voice Technologies for Reconstruction and Enhancement, De Gruyter Series in Speech Technology and Text Mining in Medicine and Healthcare, pp. 67 – 94, Feb. 2020.
  • P. Vijayalakshmi, T. A. Mariya Celin, T. Nagarajan, “Selective pole modification-basedtechnique for the analysis and detection of hypernasality”, Chapter 2 – Signal and Acoustic Modeling for Speech and Communication Disorders, De Gruyter Series in Speech Technology and Text Mining in Medicine and Healthcare, pp. 33 – 68, Dec. 2018. 

Journal publications:

  1. Lavanya, T. Nagarajan, P. Vijayalakshmi,“Multi-level single channel speech enhancement using a unified framework for estimating magnitude and phase spectra”, IEEE transactions on audio, speech and language processing (accepted for publication).
  2. Dhanalakshmi, T. Nagarajan, P. Vijayalakshmi,“ Significance of tongue and lip sensors as articulatory information in assessment of dysarthric speech”, CSSP (submitted).
  3. Anushiya Rachel, P. Vijayalakshmi, T. Nagarajan, “Analysis of Algorithms to Estimate Glottal Closure Instants from Speech Signals”, International Journal of Speech Technology (submitted).
  4. P. Actlin Jeeva, T. Nagarajan and P. Vijayalakshmi, “Adaptive multi-band filter structure-based far-end speech enhancement”, in IET Signal Processing. (Accepted for publication)
  5. A. Mariya Celin, G. Anushiya Rachel, T. Nagarajan and P. Vijayalakshmi, “Data Augmentation using virtual microphone array synthesis and multi-resolution feature extraction for isolated word dysarthric speech recognition,” in IEEE Journal of Selected Topics in Signal Processing, DOI: 10.1109/JSTSP.2020.2972161, February 2020.
  6. A. Mariya Celin, G. Anushiya Rachel, T. Nagarajan and P. Vijayalakshmi, “A Weighted Speaker-Specific Confusion Transducer Based Augmentative and Alternative Speech Communication Aid for Dysarthric Speakers”, IEEE Transactions on Neural Systems and Rehabilitation Engineering, Vol. 27, Issue 2, pp. 187-197, Feb 2019.
  7. Mrinalini, T. Nagarajan and P. Vijayalakshmi, “Pause-Based Phrase Extraction and Effective OOV Handling for Low-Resource Machine Translation Systems”, ACM Transactions on Asian and Low Resource Language Information Processing, Vol. 18, Issue 2, pp. 12:1-12:22, Feb 2019.
  8. Anushiya Rachel, N. Sripriya, P. Vijayalakshmi and T. Nagarajan, “Significance of Differenced EGG Signal as a Spectrum in Phase-Difference Computation for the Estimation of Glottal Closure Instants”, Circuits, Systems, and Signal Processing, Vol. 37, Issue 5, pp. 2074 – 2097, May 2018.
  9. Vijayalakshmi, B. Ramani, M. P. Actlin Jeeva and T. Nagarajan “A Multilingual to Polyglot Speech Synthesizer for Indian Languages Using a Voice-Converted Polyglot Speech Corpus”, Circuits, Systems and Signal Processing, Vol. 37, Issue 5, pp. 2142 – 2163, May 2018.
  10. Dhanalakshmi, T. A. Mariya Celin, T. Nagarajan and P. Vijayalakshmi, “Speech-Input Speech-Output Communication for Dysarthric Speakers Using HMM-Based Speech Recognition and Adaptive Synthesis System”, Circuits, Systems and Signal Processing, Vol. 37, Issue 2, pp. 674 – 703, Feb. 2018.
  11. Anushiya Rachel, P. Vijayalakshmi and T. Nagarajan, “Estimation of Glottal Closure Instants from Degraded Speech using a Phase-Difference-Based Algorithm”, Computer Speech, and Language, Vol. 46, pp. 136 – 153, Nov. 2017.
  12. Sherlin Solomi, P. Vijayalakshmi and T. Nagarajan, “Exploiting Acoustic Similarities Between Tamil and Indian English in the Development of an HMM-based Bilingual Synthesizer”, IET Signal Processing, Vol. 11, Issue 3, pp. 332-340, May 2017.
  13. Ramani, M. P. Actlin Jeeva, P. Vijayalakshmi and T. Nagarajan, “A Multi-level GMM-Based Cross-Lingual Voice Conversion Using Language-Specific Mixture Weights for Polyglot Synthesis”, Circuits, Systems and Signal Processing, Vol. 35, pp. 1283-1311, Apr. 2016.
  14. P. Actlin Jeeva, T. Nagarajan, P. Vijayalakshmi, “DCT derived spectrum-based speech enhancement algorithm using temporal-domain multiband filtering”, IET Signal Processing, Vol. 10, Issue 8, pp. 965-980, Oct. 2016.
  15. Anushiya Rachel, V. Sherlin Solomi, K. Naveenkumar P. Vijayalakshmi and T. Nagarajan, “A small footprint context-independent HMM-based speech synthesizer for Tamil”, International Journal of Speech Technology, Vol. 18, Issue 3, pp. 405 – 418, Sep. 2015.
  16. Sripriya, T. Nagarajan, “Estimation of glottal closure instants considering the speech signal as a spectrum”, IET Electronic Letters, Vol. 51, Issue 8, pp. 649 – 651, Apr. 2015.
  17. Bharathi, T. Nagarajan, “Speaker verification using speaker-specific-text”, in WSEAS Transactions on Signal Processing, Vol. 10, pp. 320-330, July 2014.
  18. Bharathi, C. Arunkumar and T. Nagarajan, “Improving the performance of speaker and language identification task using unique characteristics of a class”, International Journal of Speech Technology, Vol. 16, Issue 1, pp. 115-124, 2012.
  19. Vijayalakshmi, T. Nagarajan and Preethi Mahadevan, “Improving speech intelligibility in cochlear implants using acoustic models”, WSEAS Transactions on Signal Processing, Vol. 7, Issue 4, pp. 103 – 116, Oct. 2011.
  20. Vijayalakshmi, T. Nagarajan and M. R. Reddy, “Assessment of articulatory and velopharyngeal sub-systems of dysarthric speech”, International Journal of BSCHS, special issue on Biosensors: Data acquisition, Processing and Control, Vol. 14, No. 2, pp 87 -94, Jun. 2009.
  21. Lakshmi Sarada, A. Lakshmi, T. Nagarajan and Hema A. Murthy, “Automatic transcription of continuous speech into syllable-like units for Indian languages”, SADHANA, Vol.34, part 2, pp. 221-233, April 2009.
  22. Nagarajan and Hema A. Murthy, “Language identification using acoustic log-likelihoods of syllable-like units”, Speech Communications, Elsevier publications, Vol.48, pp. 913-926, 2006.
  23. Douglas O’Shaughnessy, Wayne Wang, Willian Zhu, Vincent Barreaud, Nagarajan and R. Muralishankar, “Toward better automatic speech recognition”, Canadian Acoustics Journal, Vol. 33, No. 3, pp.48-49, 2005.
  24. Nagarajan and Hema A. Murthy, “Sub-band based Group delay segmentation of spontaneous speech into syllable-like units”, EURASIP Journal on Applied Signal Processing, Vol. 17, pp. 2612-2625, 2004.
  25. Kamakshi Prasad, T. Nagarajan and Hema A. Murthy, “Automatic segmentation of continuous speech using minimum phase group delay functions”, Speech Communications, Elsevier publications, Vol. 42, pp. 429-446, 2004.
  26. Nagarajan, V. Kamakshi Prasad and Hema A. Murthy, “The minimum phase signal derived from the root cepstrum”, IEE Electronic Letters, Vol. 39, No. 12, pp. 941-942, 2003.

Google scholar link: https://scholar.google.com/citations?view_op=list_works&hl=en&user=MDXGGcMAAAAJ

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