Active auscultation may be used to determine organ (e.g., lung or heart) characteristics of users. An acoustic or piezo-electric signal (e.g., a pulse, a tone, and/or a broadband pulse) may be projected into an animal (typically human) body or thorax. The signal interacts with the body, or lungs, and in some cases may induce resonance within the body/lungs. A resultant signal may be emitted from the body which may be analyzed to determine, for example, a lung's resonant frequency or frequencies and/or how the sound is otherwise absorbed, reflected, or modified by the body. This information may be indicative of lung characteristics such as lung capacity, a volume of air trapped in the lungs, and/or the presence of COPD.
