How is 'volume' defined in the context of audio?

In the context of audio, 'volume' is defined as the perceived loudness of an audio signal. This is a subjective measure that reflects how loud or soft a sound is to the listener. Volume is often adjusted in audio mixing and production to create the desired listening experience. It can be influenced by factors such as the sound wave's amplitude—higher amplitudes typically result in louder sounds, while lower amplitudes correspond to softer sounds.

Understanding volume is critical for sound engineers and musicians as they balance different audio elements in a mix to ensure clarity and impact. The other concepts listed, such as frequency, speed of sound waves, and duration, relate to different aspects of sound but do not pertain directly to how loud a sound is perceived.