Ultrasound propagation speed is generally slower in which of the following substances?

Ultrasound propagation speed is generally slower in air compared to other substances. This is primarily because air is less dense than liquids and solids, which affects how sound waves travel through it. The speed of sound is influenced by the medium's density and elasticity. In air, the lower density results in a slower speed of sound, typically around 343 meters per second at room temperature.

In contrast, water, bone, and tissues have higher densities than air, allowing ultrasound waves to travel faster through these media. For instance, sound travels at approximately 1482 meters per second in water, about 4080 meters per second in soft tissues, and even faster, around 4080 to 4085 meters per second, in bone. This fundamental difference in propagation speed is crucial for sonographers to consider when interpreting ultrasound images, as it affects the time taken for echoes to return, influencing image clarity and accuracy.