Phonemic and Phonetic Errors in Conduction Aphasia
Creators: name: Petroski, Taylor
name: Haley, Katarina L.
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2017

description: Purpose: The purpose of this study was to characterize the relationship between phonemic and phonetic errors in conduction aphasia (CA) as well as the quality of these errors. Background: CA is a type of fluent aphasia that is characterized by phonological difficulties and substantial repetition difficulties in the context of relatively spared language functions in other areas. The clinical diagnosis of CA is often based on the Western Aphasia Profile (WAB), which is one of the most popular aphasia batteries due to its ease of administration and relatively objective scoring. The most challenging subtest score for this instrument is the fluency rating. The scale takes into consideration multiple dimensions, including phrase length, grammatical competence, and paraphasias of spontaneous speech. A score of 5-10 means the patient has fluent aphasia while a score of 1-4 indicates nonfluent aphasia. Because CA is a fluent type of aphasia, it requires a fluency rating greater than 4. However, people who are recovering from other presentation profiles may also receive this rating and a WAB diagnosis of CA due to persistent repetition difficulties. This may happen even if their presentation profile is not qualitatively indicative of the CA syndrome. Further examination of phonological difficulties can help identify the subset of people who have a more classic CA profile as those who present a high frequency of phonemic errors and a low frequency of phonetic distortion errors. By definition, the relationship between distortion errors and phonemic errors should be low in this population. Methods: The speech samples for this study came from AphasiaBank (http://talkbank.org/AphasiaBank/). 41 individuals classified as having CA on the WAB were given the Boston Naming Test (BNT), which includes a list of 15 words. The author transcribed each of the 615 words using a narrow transcription protocol with 12 diacritic marks. The frequency of omissions, additions, and substitutions were then compiled and supplemented by calculation of the edit distance between broad transcription of the target and observed production. Additionally, distortion type and frequency was evaluated for the data compilation. Results The results were consistent both with the clinical characterization of and the prediction that the relationship between distortion errors and phonemic errors would be low. The mean proportion of segments with phonemic errors was 61.79% while the mean proportion of distortion errors was 5.28%. The correlation between the two was low (r=0.16). Other results to note were the mean frequency of distorted substitutions, which was very low at 1.74%, and the frequencies of substitutions (20.44%), additions (4.50%), and omissions (11.60%). Discussion: As a group, these participants produced relatively high frequencies of sound errors without the distortion quality that is considered typical of motor speech disorders, including apraxia of speech (AOS). We are currently examining the results to determine whether a subset of the 41 speakers had a classic CA profile, with high phonemic error rate and low distortion error rate, whereas others may have presented with more evidence of a motor speech disorder (especially AOS). Additionally, we anticipate that further analysis of the specific distortion qualities will advance our understanding of what is characteristic of the CA profile.