Refers to other sounds besides human speech and music, including the sound of the natural environment, the sound of animals, the sound of machines and tools, and a variety of sounds emitted by human action.
Audio includes amplifiers, peripherals (including pressure limiters, effects, equalizers, VCDs, DVDs, etc.), speakers (speakers, horns) mixing consoles, microphones, display devices and so on add up to a set. Among them, the speaker is the sound output devices, speakers, subwoofers and so on.