A hearing aid with anti feed back system, the hearing aid including a signal path from at least one input transducer to an output transducer, a signal processing unit, acoustic environment detection capability, and a parameter generator that generates input to the setting of signal processing parameters to be used in the signal processing unit based on either manual input or from the results of acoustic environment detection, and an alert signal generator that generates an alert signal to the anti feed back system whenever one or more preselected input to the generation of signal processing parameters undergoes changes.