Final answer:
Sound consists of pitch, loudness, and timbre, with timbre being the characteristic that makes the same musical note sound different when played by different instruments, due to their unique sets of harmonics and resonances.
Step-by-step explanation:
Understanding Sound and Its Dimensions
Sound is a mechanical wave that is an oscillation of pressure transmitted through a medium such as air, water, or solid materials. Its different dimensions include pitch, loudness, and timbre. Pitch is the perception of the frequency of a sound wave. It determines how high or low the sound seems. Loudness, on the other hand, is linked to the sound wave's amplitude and is perceived as volume. Timbre is the tone quality or color of a sound, which makes it possible to distinguish different sounds that have the same pitch and loudness.
When different musical instruments play the same note, they sound different because each instrument has its own unique set of harmonics and resonances, which contributes to its distinctive timbre. This difference is due to variations in the instruments' materials, shapes, and the way they vibrate and produce sound waves. The perception of this tone quality is more subjective and ties into perceptual psychology, as it involves higher-level processes in the brain.