Generally, electro-dynamic loudspeakers are widely used for speech and music reproduction. However, the spreading sounds may become noise for non-target listeners nearby. In contrast, parametric array loudspeaker can reproduce audible sounds in a narrow area along the propagation axis utilizing the straightness of ultrasounds. Therefore, an audio-spot can be constructed by parametric array loudspeaker that the audible sound can only be heard at this spot. In this talk, the basic principles on ultrasonic audio-spot will be introduced. Recent studies on parametric array loudspeaker for performance improvement and novel applications will also be presented. Moreover, the potential applications of ultrasonic audio-spot in internet of things will be discussed.