The objective of this study was to design an Acoustic Integrity Monitoring (AIM) to monitor the integrity of the membrane especially when other techniques such as particle counting are not applicable. Based on hydrophonic sensor technology, the acoustic monitoring technique measures the noise (i.e. pressure fluctuation) due to a compromised fiber. The advantage of a hydrophonic sensor is that integrity of the membranes is monitored continuously during filtration, as compared to other methods such as air pressure tests which are non-continuous. Experiments were performed on three full-scale plants to evaluate the acoustic signal for different modules on one membrane rack unit and its evolution with time. Includes tables, figure.