Chapter 9---9.2.2~9.2.2.3

9.2.2 Testing perception of co-variation

Hypothese 1:
- listeners formulate equivalence categories in which the two sites of a lowered velum, N and V(nasal), are perceptually equivalent

Hypothese 2:
the range of variants of V(nasal) and N that listeners treat as perceptually equivaletn will differ depending on the voicing of the coda consonant


9.2.2.1 Methodological approach

1. co-varying acoustic properties
- trading with each other is taken as evidence of th ecoherence among parts of the acoustic signal that belong together

2. wavefrom-edeiting techniques
(bed, bend, bet, bent)
-three groups of pairs
a. N-only pair: /n/ duration was the only difference between pair members
b. cooperating paris: the stimulus with the shorter /n/ had less vowel nasalization than did the stimulus with the longer /n/
c. conflicting pairs: the stimulus with the shorter /n/ had more vowel nasalization than did the on with hte longer /n/


9.2.2.2 predictions

1. conflicting pairs, despite large acoustic differences between pair members, should be difficult to dscriminate--possibly more difficult than the acoustically less distinct N-only pairs

2. cooperating pairs, whose member have large acoustic differences and alrge differences in total nasalization, should be correctly judged as different

3. the expected influence of coda voicing is that the perceptual judgments of listeners will broadly reflect the distribution of V(nasal)N measures found for th eproduction of VNC(voiced) and VNC(voiceless) words, such that vowerl nasalization will have a greater influence on judgments in the voiceless than in the voiced context.


9.2.2.3 Results

(expected)
1. discrimination was most accurate for coopearating pairs, whose members differd substantially in total nasalization across the V(nasal)N sequence

(unexpected)
2. listeners also showed the expected greater sensitvity to vowel nasalization in the [t] than in athe [d] context

3. listeners who consistently discriminated the conflicting trials more poorly tha n the acoustically less distinfct N-only trials, and listeners whose overall accuracy on conflincting trials was similar to that on cooperating trials.

4. nasa murmurs are more likely to be detected when followed by silence (the voiceless closure) than when followed by glottal pulsing (the voiced closure)

5. Diffierent listeners have diffierent levels of respondence to the simuli

Chapter14---14.3.3.2~14.5

14.3.3.2 Prosodic effects on iceberg invariance

1. syllable magnitude (excursion)
- In order to remove this prosodic effect on movement speed, we need to measure the excursion as reflection of syllable magnigude.
- The effect of increased syllable magnitude may be observed mainly by the shift in time of the elemental gesture, away from the syllable center, without affecting the speed.

2. following boundary magnitude
- This effect is interpretable in a simple way if the effect of phrase-final lengthening due to the boundary is simply adjustment of the time scale toward the end of the phrase and the excursion magnitude is significantly affected by boundary magnitude only due to coarticulartory undershooting.



14.3.3.3 Segmentation for syllable duration and articulatory gap measurement

1. preformed by the program "ubedit"
- ubedit displays the articulatory trackings from the x-ray microbeam data and aligns them with the corespoding waveform and spectrogram.


14.4 Results
14.4.1 Relation of speed with articulatory syllable duration

1. scatterplots of the speed vs. articulatory ayllable duration in initial and final demisyllables
- The speed of the lower lip movement at the ice berg threshold was considered separately for the initial and final demisyllables in the word "five".
- slower speed for emphasized syllables in phrase-final position
- the latter syllables seem to have a relatively small syllable magnitude while being affected by final leanthening.


14.4.2 Relation of speed with aritculatory gap duration

1. The scatterplots indicate a weak negetive correlation of threshold crossing speed and gap duraion, showing longer gaps after all final digits.


14.4.3 Correlations of excursion, syllable duration, and boundary strength with speed

1. high percentages
- are accounted for by its linear relationship with the predictor variables in this syllable position.

2. lower percentages
- are accounted for by the same linear combination of predictors in fianl demisyllables

3. excusion in the present data appears to be the greater contributor to the prediction of speed for all speakers


14.5 Discussion

1. The results show evidence for speaker-specific treatment of the prosodic parameters of syllable duraion and boundary strength, in relation to implemetation of the velocity patterns of crucial articulator movements, both in initical and fianl demisyllables.

2. The clear relation between speed and excursion, shown by the cosistent significant influence of excursion on velocity of the movement at iceberg threshold crossing.

3. Overall prosodic rhythmic structure of the utterance has to be taken into account in predictin duraion, timing, and excursion of consonantal gestreus within the syllable.

4. Excursion reflects strong nonlinear effects of the speech-singal generating mechanism such as xonsonantal gesture saturation, while syllable duraiotn is less affected by such peripheral effects.