270 Erik R. Thomas, Norman J. Lass, and Jeannine Carpenter
Virginia University. Subjects were asked to circle, for each stimulus, either
African American or European American on an answer sheet. Results from
subjects with hearing impairments, from those whose ¿ rst language was not
English, and from those of ethnicities other than African American or Euro-
pean American were excluded from the numerical analyses.
2.2 Results and discussion
Levels of accuracy of ethnic identi¿ cations by listener group, experimental
treatment, and sex of speaker are given in Table 12.1. Three general trends are
evident in Table 12.1. First, the West Virginia listeners showed lower accuracy
than the two North Carolina groups of listeners. The speakers who produced
the stimuli were North Carolinians, and the West Virginians often associated
Southern dialect features by some European American speakers with African
American identity. However, they probably also had less daily contact with
African Americans than North Carolinians do and thus may be less familiar
with African American speech. Second, while the monotonized stimuli were
identi¿ ed with only slightly less accuracy than the unmodi¿ ed stimuli, the
schwa-converted stimuli were identi¿ ed with considerably less accuracy. This
¿ nding suggests that vowel quality information is more important than F0-de-
pendent information, but the noise that the synthesizer created on some of the
schwa-converted stimuli may have distracted listeners. Third, female speakers
were consistently identi¿ ed with slightly lower accuracy than male speakers.
Table 12.1 Overall Accuracy Levels in Experiment A
Treatment
North Carolina
African American
listeners (n=11)
North Carolina
European American
listeners (n=33)
West Vi rg i n ia
European American
listeners (n=39)
male
speakers
female
speakers
male
speakers
female
speakers
male
speakers
female
speakers
unmodi¿ ed 97.0% 95.5% 97.5% 94.8% 85.7% 80.7%
monotonized 91.3% 89.0% 94.1% 91.0% 79.0% 77.1%
schwa-
converted
78.0% 62.3% 81.9% 64.3% 73.7% 60.2%
Table 12.2 shows the same data broken down into stimuli featuring /æ/
prominently, stimuli featuring /o/ prominently, and control stimuli. It can be
observed that, in most cases, the three types of stimuli do not differ much in