Ultrasound Tongue Imaging

Enhanced ultrasound tongue imaging software

LinguaSound 3D is enhanced ultrasound tongue imaging (UTI) software that incorporates automated contour estimation and 3D modelling techniques to visualise the shape, position and movements of the tongue in real-time. The 3D model, which can be rotated 360˚, can simplify the interpretation of conventional ultrasound tongue imaging.

How LinguaSound 3D works

Ultrasound tongue imaging (UTI) is a non-invasive technique used to view the shape, position and movements of the tongue during speech. It relies on the use of high-frequency sound waves (ultrasound) to create real-time images of the tongue's internal structures and movements.

A layer of acoustic gel is applied to an ultrasound probe (transducer), which is placed beneath the chin. The transducer emits sound waves that travel through the tissues and are reflected back when they encounter different structures within the tongue. By analysing the time taken for the sound waves to return and their intensity, the ultrasound scanner generates dynamic images of the tongue's shape and motion. These ultrasound images are transferred to the host computer via USB.

How enhanced ultrasound tongue imaging works

LinguaSound 3D uses a markerless pose estimation model, based on deep neural networks (machine learning), to estimate tongue surface contours from the ultrasound images. The model was trained from hand-labelled midsagittal ultrasound images of the tongue, using the DeepLabCut toolbox. Finally, these tongue surface contours are used to animate a 3D model of the tongue and hard-palate in real-time.

Hard-palate estimation

Due to the air above the tongue surface reflecting sound waves back to the transducer, conventional ultrasound tongue imaging does not easily capture the hard-palate. LinguaSound 3D registers the extent of the tongue when it touches the hard-palate, allowing its position and size to be estimated. This procedure is illustrated in the following video:

Comparing conventional ultrasound tongue imaging with LinguaSound 3D

LinguaSound 3D, which is language independent, can simplify the interpretation of conventional ultrasound tongue imaging. A comparison of both imaging techniques is illustrated below for a normal English speaker:

	Conventional ultrasound tongue imaging	LinguaSound 3D
Velar Stop /k/
Alveolar Stop /d/
Retroflex /r/
High-Front Vowel /i/
Low-Back Vowel /a/

PC-based ultrasound scanner

LinguaSound 3D is compatible with a lightweight and compact PC-based ultrasound scanner that connects to the host computer via USB. Depending on the scan depth, frame rates of up to 100 frames per second can be achieved. The scanner is compatible with 20mm and 10mm ultrasound probes for use with adults and small children. It also uses fanless technology for silent operation, and supports a wealth of advanced image processing features.

Ultrasound probes

	Type	Frequency Range	Radius	Scan Depth	Field of View
	Convex	2.0 - 4.0 MHz	20 mm	60 - 230 mm	104°
	Micro Convex	5.0 - 10.0 MHz	10 mm	30 - 150 mm	156°

LinguaSound 3D software

The LinguaSound 3D software is Windows 64-bit compatible. It combines ultrasound imaging, tongue surface contour estimation and 3D modelling techniques to illustrate the shape, position and movements of the tongue in real-time. The 3D model consists of the tongue, hard-palate and teeth. The transparency of these articulators can be adjusted to reveal hidden structures, and the model can be rotated 360°.