A piezoelectric micromachined ultrasonic transducer array for parametric loudspeakers

• Published in: The Journal of the Acoustical Society of America Vol. 134; no. 5_Supplement; p. 4122
• Main Authors: Je, Yub, Lee, Haksue, Moon, Wonkyu
• Format: Journal Article
• Language: English
• Published: 01-11-2013
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.4831145

A parametric array is a nonlinear conversion process that can generate a highly directional sound beam with a small aperture. Since parametric sound generation requires high-intensity ultrasound for nonlinear interaction, efficient sound generation is an important issue in the practical use of parametric loudspeakers. In this study, a piezoelectric micromachined ultrasonic transducer array was investigated in order to generate directional audible sound with a parametric array. A piezoelectric micromachined ultrasonic transducer, with a micron-thick radiating plate, was verified to generate ultrasound with high-efficiency in air. Two types of unit transducers with different resonance frequencies (f1 = 100 kHz, and f2 = 110 kHz) were arranged in the transducer array to extend the frequency bandwidth. The electroacoustic efficiency of the transducer was measured to 71% at its resonance frequency. The ±3dB-frequency bandwidth of the transducer array was 17 kHz. The spatial distributions of the difference frequency wave were measured and compared with the computed data in the audible frequency range. The fabricated transducer array consumed 1 W of electric power while generating a 10 kHz-difference frequency wave with sound pressure level of 80 dB.