Interference resistant biomedical transducer

A transducer assembly for monitoring acoustic signals, comprising:

• a housing adapted to receive an acoustic diaphragm assembly;
• an acoustic diaphragm assembly received in said housing, said diaphragm assembly adapted to produce an electrical output signal in response to detection of an acoustic signal produced by a body;
• mechanical filtering means for filtering ambient acoustic signals and preventing detection of said ambient acoustic signals by said acoustic diaphragm assembly;
• said mechanical filtering means is a metal disc for maintaining positional stability of said transducer assembly with respect to the body from which said acoustic signal is detected, said metal disc being formed from stainless steel and having a mass of approximately one kilogram;
• a compliant handle attached to said housing, being formed from a flexible metal shaft, said handle cooperating with said metal disc to prevent ambient acoustic signals from being detected by said diaphragm assembly.

An interference-resistant transducer for monitoring acoustic signals, comprising:

• a housing adapted to receive a diaphragm assembly;
• a diaphragm assembly received in said housing, said diaphragm assembly comprising a piezoelectric diaphragm having first and second sides, said diaphragm having one portion polarized in a first direction and another portion polarized in a second direction;
• means for communicating an acoustic signal to said piezoelectric diaphragm to cause movement thereof, said piezoelectric diaphragm producing an electrical signal in response to said movement;
• mechanical filtering means for filtering ambient acoustic signals to prevent said ambient acoustic signals from causing movement of said piezoelectric diaphragm;
• first and second electrodes on said first side of said piezoelectric diaphragm, said first and second electrodes having opposite polarities, said first electrode being aligned with said portion of said piezoelectric diaphragm polarized in said first direction, said second electrode being aligned with said portion of said piezoelectric diaphragm polarized in said second direction;
• a third electrode on said second side of said piezoelectric diaphragm, said third electrode being aligned with said first and second electrodes in a configuration to cause said first and second electrodes to produce a differential output signal in response to the movement of said diaphragm;
• and
• means for amplifying said differential output signal to provide an electrical representation of said acoustic signal.