Abstract: A piezoelectric speaker (10) includes: a piezoelectric film (35); a fixing face (17) for fixing the piezoelectric film (35) to a support; and an interposed layer (40) disposed between the piezoelectric film (35) and the fixing face (17). The interposed layer (40) has a holding degree of 5×108 N/m3 or less.

Abstract: An active noise control system (500) includes a structure (80) and a plurality of piezoelectric speakers (10). The piezoelectric speakers (10) are disposed on a surface (80s) of the structure (80). The piezoelectric speakers (10) each have a radiation surface extending along a first direction (D1) and a second direction (D2). The first direction (D1) is a direction along which centers of the radiation surfaces of the piezoelectric speakers (10) are arranged so that the piezoelectric speakers (10) are adjacent to each other. The second direction (D2) is a direction orthogonal to the first direction (D1). The radiation surface of each of the piezoelectric speakers (10) is shorter in a dimension (L1) in the first direction (D1) than in a dimension (L2) in the second direction (D2).

Abstract: A speaker (10) includes a radiation surface (15). The radiation surface (15) has a first region (15a), a second region (15b), and a third region (15c) between the first region (15a) and the second region (15b). When an axis passing through the third region (15c) and extending away from the radiation surface (15) is defined as a reference axis (10X), the speaker (10) forms a first wavefront (16a) propagating from the first region so as to approach the reference axis (10X) and a second wavefront (16b) propagating from the second region (15b) so as to approach the reference axis (10X).

Abstract: A piezoelectric speaker-forming laminate (10) includes: a piezoelectric film (35); a pressure-sensitive adhesive face (17); an interposed layer (40) being a porous body layer and/or a resin layer disposed between the piezoelectric film (35) and the pressure-sensitive adhesive face (17); and a release layer (20) joined to the pressure-sensitive adhesive face (17). The pressure-sensitive adhesive face (17) is disposed in such a manner that at least a portion of the piezoelectric film (35) overlaps the pressure-sensitive adhesive face (17) when the piezoelectric film (35) is viewed in plan. The piezoelectric film (35) and the interposed layer (40) are allowed to be fixed to a support (80) as a piezoelectric speaker or a portion of a piezoelectric speaker by sticking the pressure-sensitive adhesive face (17) from which the release layer (20) has been removed to the support (80).

Abstract: A piezoelectric speaker-forming laminate (10) includes: a piezoelectric film (35); a pressure-sensitive adhesive face (17); an interposed layer (40) being a porous body layer and/or a resin layer disposed between the piezoelectric film (35) and the pressure-sensitive adhesive face (17); and a release layer (20) joined to the pressure-sensitive adhesive face (17). The pressure-sensitive adhesive face (17) is disposed in such a manner that at least a portion of the piezoelectric film (35) overlaps the pressure-sensitive adhesive face (17) when the piezoelectric film (35) is viewed in plan. The piezoelectric film (35) and the interposed layer (40) are allowed to be fixed to a support (80) as a piezoelectric speaker or a portion of a piezoelectric speaker by sticking the pressure-sensitive adhesive face (17) from which the release layer (20) has been removed to the support (80).

Abstract: A piezoelectric speaker (10) includes: a piezoelectric film (35); a fixing face (17) for fixing the piezoelectric film (35) to a support; and an interposed layer (40) disposed between the piezoelectric film (35) and the fixing face (17). The interposed layer (40) has a holding degree of 5×108 N/m3 or less.

Abstract: A sound reducing system (500) includes at least one sound reducing speaker for radiating a sound wave for sound reduction. The at least one sound reducing speaker includes a piezoelectric speaker (10). The piezoelectric speaker (10) includes a piezoelectric film (35), a fixing face (17) in contact with a support supporting the piezoelectric speaker (35), and a film holding portion (55) disposed between the piezoelectric film (35) and the fixing face (17). (i) The film holding portion (55) includes a pressure-sensitive adhesive layer and the fixing face (17) is formed of a surface of the pressure-sensitive adhesive layer and/or (ii) the film holding portion (55) includes a porous body layer.

Abstract: A piezoelectric speaker (10) includes a piezoelectric film (35), a first joining layer (51), and an interposed layer (40). The piezoelectric film (35) includes a first electrode (61), a second electrode (62), and a piezoelectric body (30) sandwiched by the first electrode (61) and the second electrode (62). The first joining layer (51) is a layer having pressure-sensitive adhesiveness or adhesiveness. The interposed layer (40) is disposed between the piezoelectric film (35) and the first joining layer (51). Both principal surfaces of the piezoelectric film (35) vibrate up and down as a whole.