US Patent 8934637 Electronic stethoscope

Provided is an electronic stethoscope pick-up head comprising an acousto-electrical transducer disposed in a chamber, the transducer being configured to generate an electrical signal representing acoustical vibrations, wherein the chamber further comprises a sound influencing bell defining a cavity to provide air communication between the transducer and a diaphragm attached to an outer end of the bell, wherein the diaphragm is acoustically decoupled from the transducer; and one or more ventilation air path as the only means to provide air communication between the cavity and outside of the chamber, wherein the air path is configured to restrict air flow through the air path.