2. SPPA 403 Speech Science1 Unit 3 outline The Vocal Tract (VT) Source-Filter Theory of Speech Production Capturing Speech Dynamics The Vowels The Diphthongs The Glides The Liquids

3. SPPA 403 Speech Science2 Unit 3: Articulation Capturing speech dynamics –The spectrogram

4. SPPA 403 Speech Science3 Acoustic consequence of articulation

5. SPPA 403 Speech Science4 But speech is dynamic! Previous example –Static unvarying source unvarying filter. Everyday speech –Dynamic source changes in pitch, loudness, and quality over time filter varies over time as the articulators move.

6. SPPA 403 Speech Science5 But speech is dynamic! Source-filter theory allows the pitch, loudness, and detailed shape of the source to vary over time allows the vocal tract frequency response curve to vary over time as the articulators move from one position to the next.

7. SPPA 403 Speech Science6 Representing the acoustic signal Sound pressure waveform represents amplitude and time but not frequency

8. SPPA 403 Speech Science7 Representing acoustic signal Amplitude spectrum represents amplitude and frequency but not time

9. SPPA 403 Speech Science8 Wouldn’t it be great to have a plot that has time, frequency and amplitude?

10. SPPA 403 Speech Science9 Introducing… The Spectrogram!

11. SPPA 403 Speech Science10 Time Frequency Amplitude = darkness on scale

12. SPPA 403 Speech Science11 The amplitude spectrum represents the frequency composition of a sound at a single point in time – just like a photograph capture the landscape at an instant in time frequency amplitude

13. SPPA 403 Speech Science12 Amplitude spectrum represents the frequency composition of a sound at a single point in time It is similar to a photograph capture the landscape at an instant in time

14. SPPA 403 Speech Science13 Spectrogram The spectrogram is analogous to a motion picture. –A motion picture is a series of still images sampled at some constant rate and played back in that order. –A spectrogram is a series of amplitude spectra lined up in time

15. SPPA 403 Speech Science14 Rotate 90 degrees F A F A

16. SPPA 403 Speech Science15 Rotate it so that The amplitude is Coming out of the page F A This is really narrow because it is a slice in time F Time

17. SPPA 403 Speech Science16 Dark bands = amplitude Peaks Time Freq

18. SPPA 403 Speech Science17 Advantages of spectrogram over time waveform and amplitude spectrum Provides time, amplitude and frequency on a single plot Unlike a sound pressure waveform you can see the frequency components of the signal Unlike an amplitude spectrum, you can see how these frequency components change over time

19. SPPA 403 Speech Science18 Two main types of spectrograms Wide-band spectrograms –Analogous to spectrum envelopes lined up end-to-end –Bandwith of the analyzing filter is broad (300 Hz) –The frequency resolution is not as sharp –Time resolution is very good Narrow-band spectrograms –Analogous to amplitude spectra lined up end-to-end –Bandwidth of the analyzing filter is narrow (45 Hz) –Frequency resolution is really sharp –Time resolution is not so good

20. SPPA 403 Speech Science19 Highlights harmonic structure Highlights overall shape of amplitude spectrum (spectrum envelope)