Generation of audible sound from two ultrasonic beams with dummy head

In this study, the nonlinear interaction of two sound beams with a Knowles Electronics manikin for acoustic research (KEMAR) dummy head was investigated experimentally. An audible sound was generated under two conditions: two ultrasonic beams were in parallel and at right angle. It was found that the presence of the dummy head not only increased audible sound levels in KEMAR ears owing to a head scattering effect, but also led to different sound levels in two ears owing to a head shadow effect. Experimental results demonstrated that for the two parallel ultrasonic beams, head effects slightly reduced the audible sound levels behind the dummy head, but increased the audible sound area. Furthermore, it was shown that the audible sound could be generated within the intersection zone of two perpendicular ultrasonic beams, which is useful for localized sound delivery in audio engineering.