Head-Probe Stabilisation in Ultrasound Tongue Imaging Using a Headset to Permit Natural Head Movement

Abstract

Translation and rotation movements of an
\nultrasound probe relative to the speaker’s head
\ninduce error. We examine one means of reducing
\nsuch errors, the headset stabilising system made by
\nArticulate Instruments Ltd., using a Vicon 612 3D
\nmotion analysis system during and between episodes
\nof speech. Probe movements relative to the head of
\nthe speaker were derived. The headset restricted
\nunwanted movement to the midsagittal plane even
\nthough a speaker was free to move the head naturally
\nduring utterances. Stressed low vowels moved the
\nprobe dynamically within this plane by as much as
\n10mm in extreme cases before it returned to near its
\noriginal position. Long-term slippage ranged from
\n1.4mm to 2.9mm and is within acceptable limits.