How is sound defined in physics?

Sound is defined in physics as a result of motion of a vibrating source. This definition emphasizes that sound is generated when an object vibrates, causing disturbances in the surrounding medium—usually air, but it can also be other media like water or solids. These vibrations create pressure waves that travel through the medium, which our ears perceive as sound.

Understanding that sound originates from a vibrating source recognizes the fundamental nature of how sound waves are created. For example, when a guitar string is plucked, it vibrates and generates sound waves that travel to the listener’s ear. This concept is foundational in the study of acoustics and the physics of sound.

The other options, while related to sound in different contexts, do not fully encapsulate the core definition. For instance, while sound does involve the dissipation of energy through waves, it does not precisely define what sound is. Similarly, while sound is indeed a transmission of vibrations through a medium and involves the creation of frequency by oscillation, these aspects are secondary to the primary concept of motion of a vibrating source generating sound.