Download - “Connecting the dots”
“Connecting the dots”How do articulatory processes “map” onto acoustic processes?
Stevens and House (1955)Model assumes No coupling with
Nasal cavity trachea & pulmonary
system
Stevens and House (1955)Model parameters Distance of major
constriction from glottis (d0)
Radius of major constriction (r0)
Area (A) and length (l) of lip constrictionA/l conductivity index
Figure 1.
Comparing model to real vocal tract
Stevens and House (1955)
Figure 2.
Key Goal of Study Evaluate the effect of systematically changing
each of these three “vocal tract” parameters on F1-F3 frequency
Form
ant F
requ
ency
(K
Hz)
Point of Constriction (d0) (cm from glottis)
F1
F2
F3
Figure 3.
Form
ant F
requ
ency
(K
Hz)
Point of Constriction (d0) (cm from glottis)
F1
F2
F3
Figure 3.
Point of constriction
A/l
NOTE Single intersection
between F1 & F2 in most cases
Figure5.
Point of constriction
A/l
Figure 5.
Point of constriction
A/l
Figure 7.
General Observations
∆ d0 = ∆ Vfront & Vback
↑ d0 = ↓ Vfront = ↑ F2
↑ d0 = ↑ Vback = ↓ F1
General Observations
↓ r0 = ↓ F1
↑ r0 = ↑ F1
When d0 ↑ (anterior)
↓ r0 = ↓ Vfront = ↑ F2
↑ lip rounding
= ↓ A/l
= ↓ F1 & F2
Formant Patterns for the “Noncentral” (i.e., omitting
/ú/ and /ü/) Monophthongal Vowels of American English (based on Peterson & Barney averages)
Formant Data for Men “Standard” F1-F2 Plot
r0
d0
- +
-
+
Peterson & Barney Averages (for men only) Plotted on an Acoustic Vowel Diagram
20
“normalizing” formant values
Clinical Example
22
Acoustic variables related to the perception of vowel quality F1 and F2 Other formants (i.e. F3) Fundamental frequency (F0) Duration Spectral dynamics
i.e. formant change over time
How helpful is F1 & F2?
Data Source Human Listeners Pattern Classifier
Peterson & Barney (1952)
94.4 % 74.9 %
Hillenbrand et al. (1995)
95.2 % 68.2 %
From Hillenbrand & Gayvert (1993)
How does adding more variables improve pattern classifier success? F1, F2 + F3
80-85 %
F1, F2 + F0
80-85 %
F1, F2 + F3 + F0
89-90 %
How about Duration?
Nearby vowels have different durations
___________________________________
American English Vowels Have Different Typical Durations
___________________________________
/i/ > /I/
/u/ > /U/
/A/ > /‰/
/å/ > /ú/
/Ø/ > /å/ ___________________________________ ___________________________________
Do Listeners Use Duration in Vowel Identification?
RESULTS
Original Duration: 96.0%
Neutral Duration: 94.1%
Short Duration: 91.4%
Long Duration: 90.9%
CONCLUSIONS
1. Duration has a measurable but fairly small overall effect on vowel perception.
2. Vowel Shortening (-2 SDs): ~5% drop in
overall intelligibility 3. Vowel Lengthening (+2 SDs): ~5% drop in
overall intelligibility 4. Vowels Most Affected: /å/ - /Ø/ - /ú/
/A/ - /‰/ 5. Vowels Not Affected: /i/ - /I/
/u/ - /U/
What about Duration?
What about Duration?
Some examples
What about formant variation?
Notice that some vowels – especially /A/ and /I/ – show a fair amount of change in formant freq’s throughout the course of the vowel. Is it possible that these formant movements are perceptually significant?
What about formant variation?
Naturally spoken /hAd/
Synthesized, preserving original formant contours
Synthesized with flattened formants
What about formant variation?
Conclusion: Spectral
change patterns do matter.
What about formant variation?
What do we conclude?
Sinewave Speech Demonstration
Sinewave speech examples (from HINT sentence intelligibility test):
Selected issues that are not resolved What do listener’s use?
Specific formants vs. spectrum envelope What is the “planning space” used by
speakers? Articulatory Acoustic Auditory