Infrasonic array data collected at Kīlauea Volcano, Hawai'i, during November 12--21, 2002 indicate that the active vents and lava tube system near the Pu'u 'Ō'ō vent complex emit almost continuous infrasound in the 0.3--10 Hz frequency band. The spectral content of these infrasonic signals matches well that of synchronous seismic tremor. In sites protected from wind noise, significant signal to noise ratios were recorded as far as ~13 km from the crater of Pu'u 'Ō'ō. The infrasonic recordings suggest that one or more tremor sources may be close to the surface. In addition, these results demonstrate that adequate site and instrument selections for infrasonic arrays are essential in order to obtain consistent and reliable infrasonic detections.