## 3 Results
### Test Material Composition
#### 3.2.2 Effects of Feature Type on Initial Phoneme Errors  
Based on the data obtained and because of the predominance of initial consonant errors, a further analysis of perceptual errors by feature (place, manner, and voicing) for initial consonants was conducted (Table 5). Overall, voicing errors were the most prominent production/perceptual errors noted for all three lists. These were followed by errors of omission, with the omission of the initial/h/accounting for over 90% of errors. Single-feature phoneme errors for manner and place were similar in their frequency of occurrence. While errors made by the intrusion of an additional phoneme into a listener's response were rare, several were observed. There were, however, no intrusion errors made on any item of the 30-item NIT.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**NIT** & **A** & **B** & **C** & **D** & **E** & **Overall** \\ \hline Initial & & & & & & \\ Position & 84 & 86 & 87 & 85 & 77 & 84 \\ \hline Final & 96 & 96 & 99 & 94 & 96 & 96 \\ Position & 99 & 100 & 100 & 100 & 99 & 99 \\ \hline
**CRT** & & & & & & \\ \hline Initial & & & & & & \\ Position & 81 & 86 & 84 & 76 & 82 & 82 \\ \hline Final & 99 & 99 & 99 & 94 & 97 & 97 \\ Position & 99 & 99 & 99 & 95 & 95 & 96 \\ \hline Vowel & 95 & 99 & 99 & 95 & 95 & 96 \\ \hline
**W&B** & & & & & \\ \hline Initial & 75 & 81 & 83 & 87 & 74 & 78 \\ Position & 96 & 97 & 97 & 94 & 94 & 95 \\ \hline Vowel & 96 & 96 & 98 & 97 & 99 & 97 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Intelligibility scores of speakers A, B, C, D, and E for vowels and consonants (in % age) by consonant position (word-initial vs. word-final) for the Northwestern Intelligibility Test (NIT), Consonant Rhyme Test (CRT), and the Weiss-Basili (W&B) lists.  
The NIT and W&B lists appear to be remarkably similar when compared for the overall quantity of errors by feature type. This finding is consistent both for overall errors and for individual speaker errors (see Table 5). Voicing errors accounted for a consistently greater overall percentage of the gross errors for two lists (NIT and W&B). The CRT, however, revealed a relatively reduced number of voicing errors for both the overall group and individual speaker scores. The overall number of omissions for the speaker group was somewhat less for the NIT and the W&B list than for the CRT. This was true for both the overall and individual speaker scores. The absence of any intrusion errors made on the NIT is conspicuous (Table 5), although these errors occurred relatively infrequently on the other two-word lists and, thus, had a minimal effect on production/perceptual accuracy scores.  
Upon comparison of the five speakers for errors by feature type and across the word lists, individual speaker variability was again noted. Specifically, Speaker D exhibited the lowest percentage of voicing errors across all lists. There was, however, little consistency in his remaining production/perceptual errors as determined by feature analysis. That is, the second greatest percentage of his errors on the NIT were place errors (24%); for the W&B list--omission errors (22%); and finally, for the CRT, manner errors accounted for the greatest percentage of errors (39%). Almost all of the errors observed for Speaker C were found in relation to the features of voicing and omissions. This was consistently observed across all three stimulus lists; yet very few manner, place, or intrusion errors were made by Speaker C. Generally, Speakers A, B, and E appeared similar in relation to proportion and quantity of feature errors across the specific stimulus lists evaluated.