The present invention provides a patient inhalation/exhalation device such as a spirometer, respiratory inhaler or spacer, the device comprising: at least one aperture for inlet or outlet of air into/from the device; a mouthpiece for communication with the mouth of the patient; and a body defining an air flow path extending between the aperture and the mouthpiece along which air is drawn to the mouthpiece by inhalation by the patient or air is forced towards the aperture by exhalation by the patient. The body comprises an air flow rate indicator operable to generate a sound signal to indicatewhen the air flow rate along the air flow path is at or above a predetermined minimum level. In another aspect, the present invention provides a device for indicating a desired fluid flow rate along afluid flow path through a respiratory inhaler. The device comprises an inlet aperture, an outlet aperture for fluid communication with the fluid flow path through the respiratory inhaler, and a bodydefining a second fluid flow path extending between the inlet aperture and the outlet aperture. The body comprises a connector portion for connection to the respiratory inhaler and a fluid flow rate indicator operable to generate a sound signal to indicate when the fluid flow rate along the second fluid flow path is at a predetermined fluid flow rate. The air flow rate indicators comprise a corrugated portion having at least one or a plurality of corrugations extending into their fluid flow paths.