Speech errors have been utilized since the beginning of the last century to learn
more about how speech is produced, both physically and cognitively. Collection of
speech errors has progressed from writing down naturally occurring speech errors to
recording experimentally induced speech errors to current studies, which are using
instrumentation to record acoustic and kinematic information about experimentally
induced speech errors. One type of instrumentation being used in articulatory research is
ultrasound. Ultrasound is gaining popularity for use by those interested in learning how
speech is physically produced because of its portability and noninvasiveness. Ultrasound
of the tongue during speech provides visual access to the articulatory movements of the
tongue.
This study utilizes ultrasound recordings of speech errors in two ways. In
Experiment 1, ultrasound images of participants’ tongues were recorded while they read
tongue twisters designed to elicit speech errors. The tongue twisters were CVC words or
CV syllables with onset velar or alveolar stops. Within the ultrasound video, the angle of
the tongue blade and elevation of the tongue dorsum were measured during the onset stop
closure. Measurements of tongue twisters were compared to baseline production
measures to examine the ways in which erroneous productions differ from normal
productions. It was found that an error could create normal productions of the other
category (i.e., categorical errors) or abnormal productions that fell outside the normal
categories (i.e., gradient errors).
Consonant productions extracted from ultrasound video were presented auditory
only to naïve listeners in Experiment 2. Listeners heard a variety of normal, gradient
error, and categorical error productions. Participants were asked to judge what they
heard as the onset sound. Overwhelmingly, the participants heard normal productions as
well as gradient error productions as the target sound. Categorical error productions were
judged to be different from the target (e.g., velar for alveolar). The only effect of
erroneous production appears to be a slight increase in reaction time to respond with a
choice of percept, which may suggest that error tokens are abnormal in some way not
measured in this study.
| Identifer | oai:union.ndltd.org:USF/oai:scholarcommons.usf.edu:etd-5087 |
| Date | 31 March 2006 |
| Creators | Stearns, Adrienne M. |
| Publisher | Scholar Commons |
| Source Sets | University of South Flordia |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Graduate Theses and Dissertations |
| Rights | default |
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