Systems, devices and methods for rendering key respiratory measurements accessible to mobile digital devices

An acoustic device for spirometric measurement, comprising:

• an inlet conduit configured to receive an airflow;
• a walled cavity in fluid communication with the inlet conduit, wherein an inner surface of the walled cavity is configured to guide at least a portion of the airflow;
• an acoustic outlet configured to receive at least a portion of the airflow and transduce at least a portion of kinetic energy of the received airflow into an acoustic emission including a frequency, wherein the frequency of the acoustic emission varies in response to a rate at which the airflow is provided to the inlet conduit;
• a flow controller in fluid communication with at least one of the inlet conduit, the walled cavity, and the acoustic outlet, the flow controller including a pressure relief valve;
• and
• a vent outlet,
• wherein the flow controller is configured to modify the airflow provided to the inlet conduit such that at least a portion of the airflow provided to the inlet conduit is directed to at least one of a first route that passes through the acoustic outlet and a second route that passes through the vent outlet;
• and
• wherein the flow controller is configured to modify at least a portion of the airflow provided to the inlet conduit such that a rate of change in the one or more frequency values included in the acoustic emission varies inversely with a rate of the airflow provided to the inlet conduit.