Error Characteristics Lend Specificity to Nonword Repetition Performance in Children Who Stutter With and Without Concomitant Disorders

Abstract

Purpose: In our earlier study, we found that overall accuracy on nonword repetition (NWR) lacked the specificity to differentiate among groups of children who stutter (CWS) with and without concomitant speech sound and/or language disorders and children who do not stutter (CWNS). The aim of this study was to determine whether NWR error characteristics distinguish these groups of children with different speech sound production and language abilities yielding insight into the deficits underlying poorer performance.

Method: Participants were 141 children (88 CWS, 53 CWNS). CWS were divided into subgroups based on the presence or absence of concomitant speech sound and language disorders. Children completed an NWR task composed of one- to four-syllable nonwords. Error types included omissions, substitutions, and migrations. Error location was documented across the syllables of the longest, four-syllable nonwords and within each syllable (onset, nucleus, and coda) for all nonwords.

Results: We found that error patterns characterized groups' NWR performance. Specifically, CWS groups made more errors on syllable onsets, more errors on the first and fourth syllable of the four-syllable nonwords, and more substitution errors than CWNS. CWS with concomitant speech sound and/or language disorders made more omission errors than CWNS and CWS with typical speech sound and language abilities. CWS with both a speech sound and language disorder made more migration errors than all other groups.

Conclusions: Using a data-driven framework derived from prior empirical investigations of NWR errors, this study demonstrated that error characteristics enhance the specificity of NWR by distinguishing groups of CWS with and without concomitant speech sound and language deficits. These error patterns also provide a window into the processes underlying NWR performance in CWS.

Figure 1.

Summary of the nonword repetition (NWR) error coding. Errors were classified according to error type (omission, substitution, or migration), location in the longest four-syllable nonwords (first, second, third, or fourth syllable), and location within the syllable across all nonwords (onset, nucleus, or coda).

Figure 2.

Average number of errors of each type across the groups. Migration errors distinguished children who stutter with speech sound and language disorders (CWS-SSD-DLD) from all other groups. Substitutions distinguished all CWS from children who do not stutter (CWNS), including children who stutter with typical speech sound production and language (CWS-TSSL) from CWNS.

Figure 3.

Average proportion of phonemes in error across the syllables of the longest four-syllable nonwords. Proportions of errors are presented to account for the presence of one additional phoneme in the fourth syllable of each nonword compared with the other syllables. Errors on the first and fourth syllables distinguished all children who stutter (CWS) from children who do not stutter (CWNS), including children who stutter with typical speech sound production and language abilities (CWS-TSSL) from CWNS. CWS-SSD = children who stutter with speech sound disorder; CWS-SSD-DLD = children who stutter with speech sound and language disorders.

Figure 4.

Average proportion of phonemes in error in each syllable position (onset, nucleus [vowel], and coda). Proportions of errors are presented because only the final syllable of each nonword contained a coda, but all syllables contained an onset and nucleus (vowel). Onset errors distinguished all children who stutter (CWS) groups from children who do not stutter (CWNS), including children who stutter with typical speech sound production and language (CWS-TSSL) from CWNS. Vowel and coda errors distinguished CWS with concomitant disorders (CWS-SSD, CWS-SSD-DLD) from groups with typical speech sound and language abilities (CWS-TSSL, CWNS). CWS-SSD = children who stutter with speech sound disorder; CWS-SSD-DLD = children who stutter with speech sound and language disorders.