A dispenser 1 has a source of medicament 2 with a can 3 and a metered dose valve 4 . The outlet stem 5 of the valve is fitted to a junction block 6 in a body 7 of the dispenser to which a breath actuated dose release mechanism 8 is connected for release of the medicament through a nozzle 9 . The can has an acoustic transducer 11 attached to its side wall 12 , in intimate acoustic contact. An electronic package 14 , comprising a detection circuit and a driver for a LCD display 15 are also mounted on the can wall, the transducer being connected to the circuit. The detection circuit is arranged to decrement a count shown on the LCD by one for every detection of noise of dispensing/metering of a dose from the can. The detection circuit is programmed to compare the spectrum of the noise with a known dose-dispensing spectrum and to decrement the counter according to the comparison.
