The intensity of a sound. Volume can be used to direct attention or to create mood.
- Phone alarms might be turned up louder in order to wake a sleeping person.
Other qualities of perceiving sound:
Sound is often used to orient us that something new is happening or to remind us that something is/will happen. The volume of these alerts are often user controlled, but one can imagine how layered sounds could vary in loudness.
The loudness of a sound attracts our attention, especially if we’re used to a mostly visual experience.