A method of controlling a power supply having an output activated in response to a first logic level of a control signal and deactivated in response to a second logic level of the control signal. In other aspects, a program storage medium encoded with instructions that, when executed by a processor, perform such a method and a computer programmed to perform such a method. One of the disclosed methods activates an alarm if an instantaneous value of the cuff pressure exceeds selected levels. Individual data blocks of the packet data or packet sessions are multiplexeddemultiplexed over the virtual circuit on the basis of a service specific convergence sub-layer protocol. The resulting acoustic signal is detected by a transducer and analyzed to provide the desired parameter.