Xkl: A Tool For Speech Analysis

1. Xkl: A Tool For Speech Analysis Eric Truslow Adviser: Helen Hanson

2. Outline • Introduction to speech analysis • Production mechanism • Models of speech production • Background about Xkl • Design • Pitch Detection • Labeling • Portability • Future Work

3. Outline • Introduction to speech analysis • Production mechanism • Models of speech production • Background about Xkl • Design • Pitch Detection • Labeling • Portability • Future Work

4. Speech Production Vocal Tract Frequency Reponse

5. Speech Production Vocal Tract Frequency Reponse Periodic Source

6. Speech Production Nasal cavities contribute too Output Vocal Tract Frequency Reponse Periodic Source

7. Speech Model: Basic Gain Pitch Period Vocal Tract Parameters Impulse Train Generator Glottal Pulse Model X Vocal Tract Model Random Noise Generator X Voiced/Unvoiced Decision Gain

8. Speech Model: Klatt

9. Parameters • Source characterization • Voiced or unvoiced • Frequency of periodic source • Energy distribution of a noise source • Vocal tract model • Resonant frequency (Formants), antiresonant frequencies and bandwidths

10. Outline • Introduction to speech analysis • Production mechanism • Models of speech production • Background about Xkl • Design • Pitch Detection • Labeling • Portability • Future Work

11. Background - Xkl • Developed in-house at MIT by Dennis Klatt in the 1980s, and was originally a command line tool on Vax systems. • Later was ported to UNIX and an X11/Motif GUI was added. • Currently runs on Linux. • Praat has become a very versatile alternative to Xkl, but Xkl has functionality that Praat does not.

12. Xkl – Features • Allows users to easily examine speech signals in fine detail. • Automatically computes DFT and spectrogram. • Can perform a variety of computations not available in other packages. • Averages spectra over time or waveforms • Smooth spectrum

13. Spectrogram and DFT in Xkl Spectrogram DFT and smoothed spectrum

14. Outline • Introduction to speech analysis • Production mechanism • Models of speech production • Background about Xkl • Design • Pitch Detection • Labeling • Portability • Future Work

15. Design Requirements Users surveyed wanted: • Pitch period estimator • An improved labeling system • Portability • Compatibility with multiple operating systems • Support for more audio file formats

16. Pitch Detection • How rapidly the vocal tract is excited with periodic pulses. • Carries lexical and prosodic information. • During computation we must decide whether speech is voiced or unvoiced. • Errors in computation often occur during transitions between sounds. • Errors depend on type of pitch detector being used.

17. Pitch Detection: Design • There are many different pitch detectors • Praat's was chosen because it • Outperforms other detectors (SNR, HNR) • Is readily available

18. Pitch Detection: Algorithm Time domain, autocorrelation method Frame processing determines strongest pitch candidates including unvoiced. Viterbi algorithm minimizes global cost from candidates. Praat Pitch Detector Remove Hanning Window Sidelobe Compute Global Peak Value Process Frame To Obtain Local Optimal Choices Find Path with Globally Minimum Cost Tone 4

19. Outline • Introduction to speech analysis • Production mechanism • Models of speech production • Background about Xkl • Design • Pitch Detection • Labeling • Portability • Future Work

20. Labeling • Support for reading and saving TextGrid files, for interaction with Praat [1]. • Tiers for grouping labels • Want labels to be displayed in same window as waveform • Different from Xkl's separated window layout

21. Labeling

22. Outline • Introduction to speech analysis • Production mechanism • Models of speech production • Background about Xkl • Design • Pitch Detection • Labeling • Portability • Future Work

23. Portability PortAudio a cross-platform audio library supports most operating systems simplifies software maintenance Runs on OS X Since it natively runs X11 Added support to open Microsoft .wav files.

24. Outline • Introduction to speech analysis • Production mechanism • Models of speech production • Background about Xkl • Design • Requirements • Alternatives • Final Design • Future Work

25. Future Work • Deploy to users for feedback • Finalize • Labeling • Pitch Contour • Fix bugs and add small features

26. Software Used • Eclipse – Integrated Development Environment. • Doxygen – A documentation generation system. • SVN – A version control system. • Open Motif – X Windows window managing system and widget library. • GDB – The GNU debugger. • GNU build system on OS X. • PortAudio – A multiplatform audio library.

27. Thank you for your attention. Special thanks to: • Professor Helen Hanson • Dr. Stefanie Shattuck-Hufnagel (MIT) • Dennis H. Klatt • Survey Participants • ECE Department

28. Questions?

29. References 1: Paul Boersma & David Weenink (2009):Praat: doing phonetics by computer (Version 5.1.05) [Computer program].Retrieved May 1, 2009, from http://www.praat.org/ 2: Paul Boersma, Accurate Short-term analysis of the Fundamental Frequency and the Harmonics-to-Noise Ratio of a Sampled Sound, 1993, http://www.fon.hum.uva.nl/paul/papers/Proceedings_1993.pdf