Ingressive speech errors: a service evaluation of speech-sound therapy in a child aged 4;6

Background: A pattern of ingressive substitutions for word-final sibilants can be identified in a small number of cases in child speech disorder, with growing evidence suggesting it is a phonological difficulty, despite the unusual surface form. Phonological difficulty implies a problem with the cognitive process of organizing speech into sound contrasts.

Aims: To evaluate phonological therapy approaches in the remediation of non-pulmonic speech errors. Thus, adding to evidence concerning the nature of ingressive substitutions and their remediation whilst highlighting their occurrence within child speech disorder population for practising and training speech and language therapists.

Methods & procedures: Child KO, a boy aged 4;6, was identified through a screening of speech, language and communication needs at his school. Word-final, non-pulmonic-egressive substitutes for fricatives and plosives were identified using the Diagnostic Evaluation of Articulation and Phonology (DEAP). Treatment took place in five, weekly school-based sessions with a care-giver present, and targeted two phonemes /f/ and /ʃ/ in word-final position. Word-final /s/ was monitored throughout to capture any change in other word-final fricatives. Phonemes /ɡ/ and /p/ were used as controls, as no change was expected in word-final plosives as a result of therapy targeting fricatives. Production of single words in the DEAP, pre- and post-therapy were transcribed by two independent therapists, (transcription agreement was 86.6% (pre) and 83.7% (post), with all 140 consonants within the DEAP transcribed), and change in consonants correct was analysed using a Wilcoxon test. Picture description tasks and telling of familiar stories were videoed post-therapy to analyse use of word-final fricative egression in connected speech.

Outcome & results: Percentage consonants correct in single-words post-treatment was significantly higher than pre-treatment at single-word level. Generalization of target fricatives into connected speech and modest generalization of non-target phonemes occurred.

Conclusions & implications: Although ingressive speech sounds are largely absent in the sound system of English, they do occur as speech-sound errors in child speech disorder and respond to phonological therapy within the context of home and school environment. Therefore, training in the phonetic identification of speech sounds outside the system of English is essential. Additionally, non-lexical factors associated with ingression also influence the child's intelligibility and should be explored further in future research.