What does an ultrasound measure in the context of speech science?

In the context of speech science, ultrasound primarily measures the structural density of tissues. This is achieved through the use of high-frequency sound waves that are transmitted into the body. When these sound waves hit different types of tissues, they are reflected back to the ultrasound device, which interprets these reflections to create images of soft tissues, such as the vocal folds and other structures in the vocal tract.

This imaging capability allows researchers and clinicians to visualize and assess the morphology and movement of speech-related structures during speech production. It can reveal information about the positioning and movement of the tongue, the larynx, and other anatomical features crucial for speech. The insights gained through ultrasound can be especially valuable for understanding speech disorders and for developing therapeutic interventions.

The other options, while related to speech and communication, do not accurately describe the primary function of ultrasound in this context. Ultrasound is not directly measuring pressure changes in the vocal cords, sound wave frequencies, or electrical impulses from the brain. Instead, its strength lies in providing detailed images that allow for an analysis of the physical structures involved in speech.