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Lab Preparation

Lab Preparation. Initial focus on Speaker Verification Tools Expertise Good example “Biometric technologies are automated methods of verifying or recognising the identity of a living person based on a physical or behavioural characteristic”. MATLAB. function sig = makesine (f, fs, timelen)

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Lab Preparation

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  1. Lab Preparation • Initial focus on Speaker Verification • Tools • Expertise • Good example • “Biometric technologies are automated methods of verifying or recognising the identity of a living person based on a physical or behavioural characteristic”

  2. MATLAB function sig = makesine (f, fs, timelen) t = 0:(1/fs):timelen-(1/fs); sig = sin(2*pi*f*t); plot (t, sig); grid;

  3. Speech Signals • Praat • Waveforms • F0/Pitch • Spectra • Time domain measurements & analysis • Frequency domain measurements & analysis • Male vs female speech

  4. Sounds and Speech • Words contain sequences of sounds • Each sound (phone) is produced by sending signals from the brain to the vocal articulators • The vocal articulators produce variations in air pressure • These variations are transmitted through the air as complex waves • These waves are received by the ear and signals are sent to the brain

  5. Praat: Speech Analysis Tool Waveform, Spectrogram, Pitch, Formants

  6. Waveforms • Plot of change in air pressure with time • Amplitude • Compression/Rarefaction • Speech: intensity/loudness • Frequency • Cycles per second (Hz) • Speed • Metres per second (ms-1) • Wavelength • Metres (m) / Microns / Angstroms (Å) • Related by Won’t concern us for now

  7. Fundamental Frequency

  8. Fundamental Frequency • F0 (pron. F-zero) • Rate of opening/closing of glottis • Vocal folds do not vibrate like strings but F0 is dependent on similar factors • Perceptual correlate is pitch • Do not confuse with formant frequencies F1, F2,…!!!

  9. Constant VT configuration; varying pitch

  10. Spectra • Think of a graphic equalizer • Speech made from waves of many frequencies • Spectrum plots (log) power against frequency • Peaks related to resonant frequencies in VT • Formants • Centre frequency • Bandwidth • Spectral slice • Spectrogram • Overhead view of slices against time • Darkness related to power

  11. Vowels vs Fricatives

  12. Spectrum /u/

  13. Spectrum /i/

  14. Spectrum S

  15. Constant pitch; varying vocal tract configuration

  16. Time-domain Analysis

  17. Male speech

  18. Female speech

  19. Spectral Tilt • Refers to general slope of spectrum • Higher formants are weaker than lower formants • Phonation is most significant factor • Greater spectral tilt in female speech • Ratio of lower formant amplitude to higher formant amplitude greater in males

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