What factor determines the loudness of a sound?

The loudness of a sound is primarily determined by its intensity, which is directly related to the amplitude of the sound wave. When a sound wave has a larger amplitude, it means that the pressure variations in the air are greater, resulting in higher energy carried by the wave. This increased energy translates to a perception of louder sound to our ears.

Our perception of loudness is not influenced by the frequency of the sound wave, which affects the pitch rather than loudness. Similarly, while the distance from the source of the sound affects how loud we hear it (as sound intensity decreases with distance), it does not influence the inherent loudness of the sound itself. The duration of the sound also does not play a role in determining loudness; it may influence how we perceive the sound over time, but it does not affect the amplitude or intensity of the sound wave at any given moment.

Therefore, the relationship between intensity and amplitude is the key factor in determining the loudness of a sound, making this answer accurate.