An acoustic transducer on a downhole tool sends an acoustic wave through a sensor plate in contact with drilling fluid. Vibrations of the sensor plate are indicative of the impedance of the borehole plate that may be associated with gas influx. A processor analyzes the vibrations and uses an estimated Q of the vibrations to determine gas influx. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).