What does an ultrasound examine in speech production?

An ultrasound in the context of speech production primarily examines the movements and configurations of the articulators (like the tongue, lips, and soft palate) as well as their relationship to speech sounds. It provides visual images of these structures in motion, which helps researchers and clinicians understand how these articulators shape acoustic output during speech.

The correct choice emphasizes that ultrasounds can help display how sound waves interact with the structures they pass through. This interaction is influenced by the density and position of these structures, which can affect how sound is produced and perceived. By visualizing these dynamics, practitioners can gain insights into speech production patterns and potential speech disorders.

The other options do not accurately represent the role of ultrasound in speech analysis. Muscle contractions are typically studied through other methods such as electromyography. Electrical impulses within the vocal cords pertain more to neural activity concerning phonation rather than directly related to the visual and visual feedback obtained from ultrasound. Magnetic fields are not relevant to ultrasound technology in speech; ultrasound uses sound waves, not magnetic fields, to create images of articulatory movements.