Improving the reliability of phonetic transcription in cleft lip and palate using ultrasound tongue imaging

Objective: This study investigated whether adding an additional modality, namely ultrasound tongue imaging, to perception-based phonetic transcription impacted on the identification of compensatory articulations and inter-rater reliability.
Patients and Methods: Thirty-six children aged 3 to 12 with CLP were recorded producing repetitions 5 of /aCa/ for all places of articulation with simultaneous audio and probe-stabilised ultrasound. Three types of transcriptions were performed: 1. Traditional phonetic transcription by a CLP specialist from 7 audio recording; 2. Qualitative observations from the live ultrasound by the clinician recording the data; and, 3. Qualitative ultrasound-aided transcription by two ultrasound-trained clinicians. We compared the number of consonants identified as in error by each transcriber and then classified 10 errors into eight different subcategories.
Results: Both the ultrasound-aided and traditional transcriptions yielded similar error-detection rates, however these were significantly higher than the observations recorded live in the clinic. Inter-rater reliability for the ultrasound transcribers was substantial, compared to moderate for the traditional transcribers. Ultrasound-aided transcribers were more likely to identify covert errors such as double articulations and retroflexion than the audio-only transcribers.
Conclusion: Ultrasound-tongue imaging is a useful complement to traditional phonetic transcription.