An active stethoscope or other sound detection device, including a diaphragm, at least one floating mass mounted to the diaphragm (at at least one coupling point of the diaphragm), and an acoustic transducer mounted to the floating mass. Preferably, each floating mass is configured and mounted so that as each floating mass and each coupling point of the diaphragm move in sympathy with acoustic waves (to be detected) that impinge on the diaphragm, the acoustic transducer rides with and is stabilized by the floating mass to which it is mounted and the diaphragm is stabilized by each floating mass. The acoustic transducer can be of any of many different types. For example, it can be a microphone, or an optical, capacitive, or inductive transducer. The diaphragm can have an isolating portion which absorbs acoustic surface wave energy incident thereon, or otherwise prevents or reduces transmission of acoustic surface waves through the isolating portion between regions of the diaphragm.
