Electronic stethoscope

An electronic stethoscope comprising:

• a diaphragm having a first surface configured to contact a living body, and a second surface located on an opposite side of the first surface;
• a sound sensor configured to receive vibration propagated from the diaphragm and to convert the vibration into an electric signal;
• and
• a tubular member having an inner wall surface that defines an internal space in which the vibration is propagated from the diaphragm toward the sound sensor,
• wherein the inner wall surface of the tubular member includes:
• a first inner wall surface that defines a first space on a diaphragm side,
• a second inner wall surface that defines a second space on a sound sensor side, and
• a boundary portion where the first inner wall surface is in contact with the second inner wall surface,
• wherein a volume of the first space is larger than a volume of the second space, and
• wherein a cross-sectional area of a transverse section of the internal space of the tubular member intersecting with a direction of extension of the internal space gradually decreases from an end on the diaphragm side toward the boundary portion in the first space and gradually increases from the boundary portion toward an end on the sound sensor side in the second space.