A method of providing instruction on the performance of chest compressions includes providing a series of signals of a first type corresponding to the desired rhythm of delivery of chest compressions in a chest compression series, and providing signals of a second type which indicate a desired point in the first series. The desired point may be a point near the end of the chest compression series. The signals of the second type may be a voiced countdown to the end of the compression series. The signals of the first type may be a series of identical sounds delivered in the desired rhythm for chest compressions, and the signals of the second type may be sounds distinct from those of the first type which correspond to the rhythm of the last N compressions in the series. The desired point in the first series may include a first point at a desired interval from the first compression, where the interval is measured in number of compressions or elapsed time. A protocol may be chosen between a protocol for a patient with a secured airway and one for a patient with an unsecured airway.