Sensor unit and musical instrument

A sensor unit configured to be attached to a vibrating body to detect a vibration of the vibrating body, the sensor unit comprising:

• a sheet-like piezoelectric element having a porous layer, a first electrode layer, and a second electrode layer, the porous layer being disposed between the first electrode layer and the second layer, the sheet-like piezoelectric element being configured to generate a voltage in accordance with an amount of compression of the porous layer in a thickness direction of the porous layer;
• a sound propagation sheet that covers at least one face of the sheet-like piezoelectric element, the sound propagation sheet being configured to permit sound that is incident on a first face of the sound propagation sheet to be transmitted toward a second face of the sound propagation sheet;
• and
• a sheet-like weight having a substantially uniform thickness and being disposed on the sheet-like piezoelectric element such that the sheet-like weight covers the sheet-like piezoelectric element, the sheet-like weight and the vibrating body being disposed on opposite sides of the sheet-like piezoelectric element from each other,
• wherein the sound propagation sheet includes a first sound propagation sheet and a second sound propagation sheet, the piezoelectric element being disposed between the first sound propagation sheet and the second sound propagation sheet,
• wherein an outer periphery of the first sound propagation sheet corresponds to an outer periphery of the second sound propagation sheet in a cross-sectional view, and the outer periphery of the first sound propagation sheet and the outer periphery of the second sound propagation sheet are disposed at positions outside a first distal end and a second distal end of the sheet-like piezoelectric element in the cross-sectional view,
• wherein the sheet-like weight is disposed on the first sound propagation sheet such that the first sound propagation sheet is disposed between the sheet-like weight and the sheet-like piezoelectric element with the sheet-like weight not extending beyond the first distal end and the second distal end of the sheet-like piezoelectric element in the cross-sectional view.