Which effect does amplitude modulation have on sound?

Amplitude modulation primarily affects the volume of a sound. When amplitude modulation is applied, the amplitude of the sound wave is varied, which results in changes in how loud or soft the sound is perceived by the listener. This technique is often utilized in various audio applications to create dynamic effects that give the sound a sense of movement or variation in intensity.

To clarify further, other aspects such as tone, pitch, and timbre remain constant when only the amplitude is altered. Tone generally relates to the frequency or quality of the sound rather than its volume, while pitch pertains to how high or low a sound is perceived. Timbre, on the other hand, involves the character or color of the sound that distinguishes different types of sound production. In short, while amplitude modulation effectively enhances or reduces volume, it does not inherently change the other attributes of sound itself.