Summary: Acoustic energy harvesters that function in environments where sound pressure is extremely high (150 dB), such as in engine rooms of aircraft, are expected to be capable of powering wireless health monitoring systems. This paper presents the power generation performance of a lead-zirconate-titanate (PZT) acoustic energy harvester with a vibrating PZT diaphragm. The diaphragm had a diameter of 2 mm, consisting of Al (0.1 µm)/PZT (1 µm)/Pt (0.1 µm)/Ti (0.1 µm)/SiO2 (1.5 µm). The harvester generated a power of 510-14 W under a sound pressure level of 110 dB at the first resonance frequency of 6.28 kHz. It was found that the generated power was increased to 2.010-13 W using a sound-collecting Helmholtz resonator cone with a height of 60 mm. The cone provided a Helmholtz resonance at 5.8 kHz, and the generated power increased from 9.710-15 W to 7.310-13 W at this frequency. The cone was also effective in increasing the bandwidth of the energy harvester.