A Reader in Sociophonetics

308 Thomas C. Purnell

and ABSOLUTE DURATION (pulsing duration, vowel duration) as the second
component. Thus, we can observe the contrast between temporal and spectral
cues to voicing in Wisconsin English, the combination of percent glottal pulsing
and vowel duration in Wisconsin English, the dominance of pulsing in group
2, and the opposition—rather than the combination—of percent glottal pulsing
and vowel duration in group 5. It is interesting to note that the grouping of the
group 3 perceptual data, which parallel group 5 in terms of measures selected
by the model, follow the Wisconsin English models which place vowel duration
and percent glottal pulsing on opposite dimensions (speci¿ cally, like group 2
and not like group 4). The latent factors for the perceptual group 3 data might,
then, be interpreted as PULSING and VOWEL DURATION.
Visual relations between variables are depicted in eigenvector plots in
Figures 13.3 through 13.8. Since we would like to know how measures relate
to each other and how this relation changes over time, we use the eigenvec-
tors as weights for each measure. The plots show the sums of two measures
times the actual value for the appropriate measure. The goal of these plots
is to depict the variable space so that we can understand the contribution of
each variable to the overall discriminant space. In the case at hand, pairs of
measures are used for each axis and the best principal component across both
voiced and voiceless tokens.

Table 13.7 Multivariate Results of Principal Component Analysis

Group

Voiceless Tokens Principal

Component Eigenvalue

Voiced Tokens Principal

Component Eigenvalue

1 2 1 2

1: 1866–1892 1.865

(0.466)

1.197

(0.765)

1.733

(0.433)

1.017

(0.688)

2: 1899–1918 1.964

(0.491)

1.452

(0.854)

2.146

(0.537)

1.318

(0.866)

3: 1920–1939 1.484

(0.371)

1.144

(0.657)

1.373

(0.343)

1.214

(0.647)

3: Perception 1.641

(0.410)

1.134

(0.694)

2.121

(0.530)

1.453

(0.893)

4: 1966–1986 1.437

(0.359)

1.065

(0.625)

1.565

(0.391)

1.074

(0.660)

5: Cont rols 1.655

(0.414)

1.359

(0.753)

1.716

(0.429)

1.176

(0.723)

Note: Cumulative proportions appear in parentheses.