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Open AccessArticle

A Critical Step to Using a Parametric Array Loudspeaker in Mobile Devices

1
Department of Mechanical Engineering, POSTECH, Pohang 37673, Korea
2
Department of Electrical Engineering, Pukyoung National University, Busan 48513, Korea
3
Department of Ocean System Engineering, Jeju National University, Jeju 63243, Korea
*
Author to whom correspondence should be addressed.
Sensors 2019, 19(20), 4449; https://doi.org/10.3390/s19204449
Received: 22 August 2019 / Revised: 8 October 2019 / Accepted: 10 October 2019 / Published: 14 October 2019
(This article belongs to the Special Issue Piezoelectric Transducers)
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. View Full-Text
Keywords: parametric array; directional speaker; piezoelectric micro-machined ultrasonic transducer parametric array; directional speaker; piezoelectric micro-machined ultrasonic transducer
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Ahn, H.; Been, K.; Kim, I.-D.; Lee, C.H.; Moon, W. A Critical Step to Using a Parametric Array Loudspeaker in Mobile Devices. Sensors 2019, 19, 4449.

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