A reed includes: a reed main body having a plate shape, the reed main body including a fixed part fixed to a mouthpiece, and a vibrating part that extends from the fixed part and vibrates; and a sensor part that is disposed inside the vibrating part or on an inner surface of the vibrating part, the inner surface of the vibrating part facing the mouthpiece, the sensor part comprising an effective sensor portion that detects vibration of the vibrating part.

An information reception device is provided with: operation surface which is adjusted to produce a characteristic index vibration by an object contact; a storage device stores candidate information (candidate information is related with the index vibration) which serves as a candidate of input information; a microphone which acquires observation information according to observation of the actual vibration arising in the surrounding environment; and a CPU. The CPU (selecting part) judges whether or not the index vibration exists in the observation information acquired. When the CPU judges that the index vibration exists, the CPU selects the candidate information which is related with the index vibration as the input information.

A drum head includes: a first film including a striking surface; a second film disposed opposed to a back surface of the first film which is back from the striking surface; and a sensor disposed between the first film and the second film and configured to output a signal related to vibration. The sensor includes: a first contact surface configured to contact the back surface of the first film without being secured to the back surface; and a second contact surface configured to contact a front surface of the second film without being secured to the front surface. A sensor tail of the sensor is secured to at least one of the first film and the second film located outside the shell when the first film and the second film are stretched over an open end of a shell.

Provided are a pickup sensor and a biological sensor that are small-sized and can detect micro vibration efficiently and stably with high accuracy. The pickup sensor includes an electroacoustic converter film including: a piezoelectric polymer composite in which piezoelectric particles are dispersed in a viscoelastic matrix that is formed of a polymer material having viscoelasticity at normal temperature; two thin film electrodes that are laminated on opposite surfaces of the piezoelectric polymer composite, respectively; and a protective layer that is laminated on at least one of the two thin film electrodes, in which at least a part of a surface of the electroacoustic converter film is an abutting surface that abuts against a test object, and the thin film electrode on a surface opposite to the abutting surface is grounded.

An omnidirectional electroacoustic transducer capable of reproducing a sound with high acoustic quality and sufficient sound volume in a wide frequency band is provided with a small number of components. The electroacoustic transducer includes: two or more electroacoustic transduction units each including an electroacoustic transduction film and an elastic supporter, the electroacoustic transduction film having a polymer composite piezoelectric body in which piezoelectric body particles are dispersed in a viscoelastic matrix formed of a polymer material having viscoelasticity at a normal temperature, and two thin film electrodes laminated on both surfaces of the polymer composite piezoelectric body, and the elastic supporter being disposed to be closely attached to one principal surface of the electroacoustic transduction film so as to cause the electroacoustic transduction film to be bent, in which the two or more electroacoustic transduction units are disposed so that the electroacoustic transduction films face outward and form some or all of faces of a polyhedron.

A reed includes: a reed main body having a plate shape, the reed main body including a fixed part fixed to a mouthpiece, and a vibrating part that extends from the fixed part and vibrates; and a sensor part that is disposed inside the vibrating part or on an inner surface of the vibrating part, the inner surface of the vibrating part facing the mouthpiece, the sensor part comprising an effective sensor portion that detects vibration of the vibrating part.

A drum head includes: a first film including a striking surface; a second film disposed opposed to a back surface of the first film which is back from the striking surface; and a sensor disposed between the first film and the second film and configured to output a signal related to vibration. The sensor includes: a first contact surface configured to contact the back surface of the first film without being secured to the back surface; and a second contact surface configured to contact a front surface of the second film without being secured to the front surface. A sensor tail of the sensor is secured to at least one of the first film and the second film located outside the shell when the first film and the second film are stretched over an open end of a shell.

A sensor unit capable of protecting a piezoelectric element and detecting vibration and sound is provided. The sensor unit comprises a sheet-like piezoelectric element having a porous layer, and a sound propagation sheet covering at least one face of the piezoelectric element and permitting transmission of sound from a first face toward a second face of the sound propagation sheet. A difference in acoustic pressure level between the sound incident on the sound propagation sheet and the transmitted sound is preferably no greater than 10 dB. A surface density of the sound propagation sheet is preferably from 0.03 g/m.sup.2 to 100 g/m.sup.2. The sound propagation sheet is preferably flexible and preferably has voids. The sensor unit preferably further comprises a sound insulation sheet covering another face of the piezoelectric element and substantially preventing transmission of sound from a second face toward a first face of the sound insulation sheet.

Provided are an electroacoustic transduction film capable of reproducing a sound with a sufficient sound volume at a high conversion efficiency, a manufacturing method thereof, an electroacoustic transducer, a flexible display, a vocal cord microphone, and a sensor for a musical instrument. The electroacoustic transduction film includes: a polymer composite piezoelectric body in which piezoelectric body particles are dispersed in a viscoelastic matrix formed of a polymer material having viscoelasticity at a normal temperature; two thin film electrodes laminated on both surfaces of the polymer composite piezoelectric body; and two protective layers respectively laminated on the two thin film electrodes, in which an intensity ratio .sub.1=(002) plane peak intensity/((002) plane peak intensity+(200) plane peak intensity) between a (002) plane peak intensity and a (200) plane peak intensity derived from the piezoelectric body particles in a case where the polymer composite piezoelectric body is evaluated by an X-ray diffraction method is more than or equal to 0.6 and less than 1.

A mouthpiece includes a body, a piezoelectric sensor, and a support structure. The body defines a conduit for air. The piezoelectric sensor includes a piezoelectric element having a porous layer compressable and deformable by vibration of the air. The piezoelectric sensor is configured to generate a detection signal based on compression and deformation of the porous layer. The support structure supports the piezoelectric element in the conduit.