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 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,…!!! Fundamental Frequency

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 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 Spectral Tilt