A method is provided for analyzing respiration of a subject (20). Using a non-contact microphone (22), a raw signal indicative of air-flow sounds of the respiration is generated. The raw signal is analyzed to determine a first set of one or more parameters of the respiration. An algorithm is applied to the first set of one or more parameters of the respiration. An algorithm is applied to the first set of parameters to derive a second set of one or more estimated parameters of the respiration that are not generally directly measurable in the raw signal. Other embodiments are also described.