Some of us here have an interest in electrostatic audio speakers and headphones. This stethoscope looks like the reverse of that idea, to use as a microphone. Electrostatic speakers, which vibrate a charged membrane between two wire meshes, are known to be much more responsive than traditional, and we assume the same would be true for microphones.

Thinklabs Medical LLC, a Centennial, CO company, explains its cool product:

The ds32a is a diagnostic electronic stethoscope with unsurpassed natural sound quality. User-friendly design and 50X Amplification provides the power to adjust for faint heart sounds, obese patients, or noisy environments. Outstanding performance and ease-of-use for every clinician, with uncompromised features for advanced users. From BP to ED to ICU, from heart and lung exams to iPod recording, the ds32a does it all...

In a conventional stethoscope, the diaphragm vibration causes air pressure behind the diaphragm to change, which passes up the tubes as a sound wave to impinge pressure changes on the listener's eardrums. Losses occur through the tubing and there is no amplification.

Thinklabs developed a technology that replaces air pressure changes with electric field changes. Having captured diaphragm movement as an electrical signal, it can be amplified and processed with the full power of current technology. The resulting electrical signal is a perfect analog of the air pressure changes at the diaphragm of a traditional stethoscope, ensuring that the electrical signal truly captures the authenticity of stethoscope sound enabling you to use a Thinklabs stethoscope with no "ear re-training".

Thinklabs diaphragm technology has been implemented as the Electromagnetic Diaphragm (EmD) used in Thinklabs stethoscopes. The EmD is coated internally with a conductive surface. Spaced behind the diaphragm is a metal plate which is charged to a high voltage, thereby setting up an electric field behind the diaphragm. As the diaphragm moves, the voltage on the plate changes due to changes in the electric field. The beauty of this solution is that the diaphragm moves exactly as it would in a conventional stethoscope, and therefore the vibratory response is identical. The result is a sound familiar to the clinician, but amplified and processed to extract the optimal frequency response.

Company's website...

UPDATE: Company rep tells us that we were correct in our assumptions: "The capacitive sensor is indeed the sensor counterpart of electrostatic speakers, and yes, our diaphragm is far more responsive and natural than alternatives such as piezo-electric sensors."