How is sound defined in a scientific context?

Sound is defined in a scientific context as a mechanical energy that travels through a medium. This means that sound is created by the vibration of molecules within a medium—such as air, water, or solid materials—which causes pressure waves to propagate. When an object vibrates, it causes nearby particles of the medium to vibrate as well, transmitting the energy through the medium until it reaches our ears.

Understanding sound as mechanical energy also underscores its requirement for a medium to travel; unlike light, which can propagate through a vacuum, sound cannot exist without the presence of molecules to carry its waves. This crucial aspect of sound distinguishes it from forms of energy associated with light, electricity, or chemical reactions, making the correct definition focused on its mechanical nature and the necessity of a medium for transmission.