Development and Validation of Therapy Protocol for Compensatory Articulation in Children with Repaired Cleft Lip and Palate

Abstract

Cleft lip and palate (CLP) is one of the most common congenital anomalies affecting the oro-facial region. Children with cleft lip and palate encounter challenges, primarily in the production of speech. Due to the anatomical variations resulting from the cleft, individuals may develop unique strategies to overcome speech impediments and communicate effectively, resulting in compensatory articulation. Several therapy techniques exist to eliminate compensatory articulation in individuals with CLP. However, the effectiveness of these techniques remains unexplored in the Indian context, especially in the Kannada language. Moreover, there are no comprehensive resource manuals on articulation therapy in the Kannada language for minimising compensatory articulation.

Thus, the current study aimed to develop and validate an articulation therapy protocol that aids in reducing compensatory articulation for stop consonants in children with repaired cleft lip and palate. The study was conducted in two phases. The first phase focused on developing an articulation therapy protocol to minimise speech sound errors for stop consonants in children with repaired cleft lip and palate. The second phase highlights validating the therapy protocol for children with compensatory articulation secondary to repaired cleft lip and palate. In the first phase of the study, the focus was on reviewing, compilation, and organisation of materials, strategies, principles, and techniques to minimise compensatory articulation errors. Further, the content of the developed protocol was validated. Subsequently, appropriate stimuli and materials were chosen and validated for the assessment and therapy, with careful consideration given to the perceptual and acoustic features of the target phonemes.

In the second phase, the validation of the articulation therapy protocol to minimise compensatory articulation in children with repaired cleft lip and palate was carried out. A 'single-subject design with multiple baselines across behaviours' research design was used, with a purposive sampling technique. The current study consisted of children between 3 and 7 years of age in two groups: Group I included ten participants with compensatory articulation secondary to repaired cleft and palate, while Group II comprised typically developing children. Further, the validation was conducted in three phases: (a) the pre-treatment phase; (b) the intervention phase, spanning over 30 sessions of articulation therapy; and (c) the post-intervention phase. In the pre-treatment phase, a baseline assessment using perceptual and acoustic measures was carried out. Based on the results obtaine, the intervention phase was initiated. The intervention phase was further classified into two phases: (a) the auditory discrimination phase and (b) the production training phase. After the intervention phase, the post-intervention phase was carried out, where post-therapy assessment was done based on the perceptual and acoustic measures. Thus, for Group I, the assessment was carried out at four time points [Baseline (B), after 10 sessions (A1), after 20 sessions (A2), and after 30 sessions (A3)], and in Group II, the data were collected for acoustic analysis at a single instance. The analysis of the data comprised perceptual and acoustic measures to evaluate the effectiveness of the developed protocol for children with RCLP.

The obtained data during the four time points was studied based on perceptual and acoustic methods. The perceptual methods included: substitution, omission, distortion, and addition (SODA) error analysis method; place, Manner, and Voicing (PMV) error analysis method; cleft type error (CTE) analysis; and percent consonant correct-revised (PCC-R). The acoustic measures included: burst duration (BD), voice onset time (VOT), word duration (WD), preceding vowel duration (pVD), following vowel duration (fVD), syllable duration (SyD), total duration (TD), closure duration (CD), formant frequencies and bandwidth, and F2-onset frequency.

During the baseline assessment, the results of the perceptual evaluation using SODA error analysis indicated the presence of substitution, distortion, and omission errors in word-initial and medial positions. Further, substitution errors were observed to be the highest, followed by distortion and omission errors in the word-initial position. In the word medial position, substitution errors were highest, followed by distortion errors. Place, manner, and voicing analysis indicated 70% errors in terms of place of articulation, 16.25% in terms of manner, and 45.41% in voicing. Further, CTE analysis indicated the presence of glottal stop, weak oral pressure consonant, nasalized voiced pressure consonant, nasal consonant for oral consonant, velar, mid-dorsum palatal stop, pharyngeal stop, voicing error, and other errors in varying percentages during baseline assessment. Acoustic analysis indicated varied values in the temporal and spectral parameters when compared with Group II. Further, a Mann-Whitney U test was performed, and significant differences were observed in temporal parameters: burst duration, voice onset time, word duration, closure duration, total duration, and syllable duration. The spectral parameters F2, F3, B2, B3, and F2 onset frequency were also found to be significantly different. Further, it was observed that the maximum difference was present for the vowel /i/, followed by /u/ and /a/.

The intervention phase comprised 30 sessions of articulation therapy. Therapy was provided based on the protocol for each child in Group I based on the errors observed, and periodic assessments were carried out. After 30 sessions of therapy, the post-intervention phase assessment was carried out. The perceptual measures indicated a shift in the type of error with every consecutive assessment. In word-initial position, the final assessment (A3) indicated the persistence of weak oral pressure consonants, voicing errors, pharyngeal stops, and nasalized voiced pressure consonants. In the word-medial position, the persistence of weak oral pressure consonants, voicing errors, pharyngeal stops, nasalized voiced pressure consonants, and velar stops were observed. It was also noted that the cleft-type errors, though present, were minimal, whereas the correct productions increased largely. The error patterns in each participant were observed to vary with progress in therapy due to the heterogeneity of the population. Further, descriptive statistics were carried out for the acoustic measures in both groups. The results obtained indicated a longer duration for the temporal parameters: BD, VOT, WD, TD, and CD. Whereas varied values were observed in the remaining temporal and spectral parameters. Further, the Mann-Whitney U test was performed, and the results indicated significant differences in a few of the temporal and spectral parameters when the A3 of children with RCLP were compared with TDC.

A positive shift in the articulatory productions, with articulation therapy was observed in children with cleft lip and palate, which was reflected perceptually and acoustically. This indicates that the developed therapy protocol benefited children with repaired cleft lip and palate by minimising articulatory errors.