The production and perception of /t, d/-glottalization and vowel variation in Black
and White Dialects of Houston English
Nancy Niedzielski [Rice University]
In this talk I will report on work the Chris Koops and I have done on the production and
perception of ethnicity in dialects of Houston English. For instance, we have explored
the correlation between the glottalization of word-final /t/ and /d/ (e.g. seat, seed) and
vowel variants in the speech of younger speakers of Houston African-American English
(AAE). Our findings show that in Houston AAE, as in most dialects of English, postvocalic, word-final /t/ is variably released, unreleased, or glottalized. But while both
younger EAE and AAE speakers use these variants of /t/, the variation found for /d/ is far
greater in AAE. We present word-list data showing that while both /d/ and /t/ display
glottalization effects, the amount and the phonetic quality of glottalization differs, and /d/
can be completely deleted in AAE. At the same time, Houston AAE speakers’ vowel
systems also differ substantially from those of younger EAE speakers, including the
raising of the front lax vowels (did, dead, dad) and fronting of / / (job), as well as strong
raising of / / (cut). Speakers show varying degrees of use of these AAE vowel features,
however, and we find that the degree to which speakers demonstrate glottalization and
deletion of /d/ is highly correlated with the degree to which they use AAE vowel variants.
Next, we aimed to test listeners’ knowledge of this local glottalization pattern
Following the methodology of Pierrehumbert and Frisch (1997) we used speech synthesis
to closely mimic the acoustic effects of glottalization by rapidly decreasing f0 and
compensating for reduced intensity by adjusting the amplitude of voicing. In this way, a
set of highly realistic words with final glottalization was produced, and each word could
be interpreted as ending in either /d/ or /t/. In order to encourage the /d/-interpretation, we
created a vowel duration continuum extending into the range normally associated with a
pre-voiced context. Participants heard these stimuli in the guises of both AfricanAmerican and White speakers. We found three highly significant correlations to the
degree of /d/-responses: 1). Listeners gave more /d/-responses in the African American
speaker condition than in the White speaker condition; 2). /d/-responses were
significantly correlated with the use of AAE vowels, and; 3). The degree of familiarity
with AAE significantly correlates to degree of /d/-responses. This bears out the
prediction that knowledge of sociophonetic variation and ethnicity includes fine-grained
and subconscious knowledge of such localized dialect features, and that greater exposure
to dialect differences increases this knowledge. Finally, we found that expectations about
the speakers had an effect on the perception of the synthesized samples: