Abstract: A device for measuring microphone sensitivity and droop by subjecting the microphone to a negative step function input and recording the microphone electrical response thereto. The microphone is surrounded by an inflated thin, flexible, expandable membrane. The membrane is ruptured resulting in an instantaneous reduction in air pressure on the microphone. It is this instantaneous reduction in air pressure that constitutes the negative step function input to the microphone.

Abstract: A device for measuring the statistical distribution within a discrete range f a measured continuous variable. A conventional type meter which employs a scaling amplifier in series with weighted filters, a true RMS detector and time averager is used to detect the variable level and convert it to a analogue voltage of magnitude proportional to the magnitude of the variable at any given instant. The voltage signal is then passed through a scaling amplifier to an analogue to digital converter. The converter is controlled by a timer with an adjustable rate in such a way that the converter output is pulsed. Each level of the digital output is connected to a counter. Since each level corresponds to a discrete range of magnitudes of the variable, the percent time within a given discrete range can be calculated from the ratio of the pulses counted at a given level to the total number of samples taken.