A sensor for froth acoustic emission detection, capable of isolating the external noise produced by machinery in the concentrator, has been recently developed and tested. The froth acoustic emission technique involves the use of ultrasonic sensors to measure the elastic energy released by film rupture during bubble coalescence in industrial flotation cells. The signal emitted by the sensor has been proven to respond to changes in froth conditions. This signal, the acoustic emission activity of the froth phase, provides an alternative method to measure the stability of the froth. This device has been recently tested in industrial size flotation cells, measurements were performed in different cells along a flotation bank where differences in the froth phase between cells can be appreciated in steady state. The sensor has also been tested in a pilot cell (3 m(3)), operating with different frothers and concentrations. The response of the sensor to changes in metallurgical performance are shown in this paper and compared with other instrumentation outputs. (C) 2008 Elsevier Ltd. All rights reserved.