Magnitude of ultrasound probe misalignment measures in controlled conditions - a case study

Absztrakt

We report a method development study aimed for evaluating the reliability of tongue ultrasound data. We analyse the use mean squared error (MSE) of the means ultrasound recordings as a metric of probe stability. The metric’s performance is evaluated against systematically varied speech materials (fronted articulation versus backed articulations) and probe displacement. The speech materials consist of 54 different /CVCVCV/ utterances in random order produced by one native speaker of Finnish and recorded with a Micro ultrasound setup using Articulate Assistant Advanced. In the fronted condition the vowel is /i/ and consonants are varied among /n,s,t/. In the backed condition the vowel is /o/ and the consonants are varied among /h,k,N/. The probe displacement is both simulated and produced intentionally in the real world. For the latter the 54 utterances were repeated in a second block in a different random order. The differences between the results the two displacement methods indicates that this dual approach merits further study. The results also indicate that varying speech materials may overshadow probe displacement which leads to a tentative recommendation of comparing like with like in speech materials when using MSE to detect probe movement.