Abstract
A parametric array (PA) loudspeaker is a highly directional audio source that might grant one's convenience if it is used with mobile devices. However, conventional PA loudspeakers is almost impossible to apply in mobile devices using a battery because of the large power consumption and large device size. In this study, a PA loudspeaker system (PALS) was fabricated and evaluated to show that those difficulties could be overcome to apply it to mobile devices. In order to construct a PALS for demonstration, a power amplifier and signal-processing unit should also be properly designed and built. The PA source transducer should also be designed and built for a mobile device application. These components were integrated into a single PALS. The PALS generated a 125-dB primary wave and 62 dB of a different frequency wave (DFW) through the PA at 0.45 m in a 3 m × 3 m × 2 m semi-anechoic chamber. We confirmed that the half-power bandwidth (HPBW) formed a 6° beam at 83 kHz of DFW and 90 kHz of the primary wave (PW), and the HPBW formed a 7.3° beam at 5 kHz of DFW and a 7.1° beam at 10 kHz of DFW, respectively. Lastly, the power required was 6.65 W without a matching circuit, and 3.25 W with such a circuit.
Highlights
The parametric array (PA) loudspeaker is a highly directional audio source that may be useful in special environments such as museums, exhibitions, and galleries, as well as for multi-language teleconferencing not widely known to the public
This study investigates the possibility of applying the PA loudspeaker to mobile devices
We developed a packaged compact PA loudspeaker system (PALS)
Summary
The parametric array (PA) loudspeaker is a highly directional audio source that may be useful in special environments such as museums, exhibitions, and galleries, as well as for multi-language teleconferencing not widely known to the public. Since this loudspeaker generates audible sounds through the PA phenomenon via finite amplitude acoustic progressive waves [1,2], the directivity of the radiating audible sounds is much higher than those from conventional loudspeakers of a comparable size. Because the PA phenomenon is a second-order nonlinear effect observed during propagation of progressive acoustic beams with finite amplitudes, the generated audible sounds are very weak and the waveforms are difficult to control. Typical PA loudspeakers on the market usually have high power consumption, low sound quality, and a large size relative to their maximum
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