An acoustic diaphragm made at least in part from an expanded material. The expanded material includes one or more of cellulose, synthetic fibers and glass fibers. The expanded material has more than about 55% by volume voids.

A speaker diaphragm includes a plurality of highly rigid layers and a porous layer. Each of the plurality of highly rigid layers includes a first resin matrix, and wood fibers and highly rigid fibers dispersed in the first resin matrix. The porous layer includes a second resin matrix comprising independent pores, and fibers comprising wood fibers and highly rigid fibers dispersed in the second resin matrix. Both outermost layers are the highly rigid layers. A percentage content of the wood fibers in the highly rigid layers is 10% by mass or more and 65% by mass or less. A percentage content of the highly rigid fibers in the highly rigid layers is 5% by mass or more and 40% by mass or less. A percentage content of total fibers in the porous layer is 15% by mass or more and 40% by mass or less.

A non-dispensing manufacturing process includes forming a paper cone; engaging the paper cone with a voice coil to form a vibration assembly; fixing a yoke, a magnet set, and a washer to form a magnetic circuit assembly; engaging a basket with the magnetic circuit assembly; and engaging the basket with the vibration assembly to form a speaker, where no glue is used in the manufacturing process. A speaker includes a paper cone; a voice coil engaged with the paper cone to form a vibration assembly, where a junction between a bobbin of the voice coil and the paper cone has a first welding layer; a magnetic circuit assembly including a yoke, a magnet set, and a washer that are integrally fixed; and a basket engaged with the magnetic circuit assembly and the vibration assembly.

An acoustic diaphragm made at least in part from an expanded material. The expanded material includes one or more of cellulose, synthetic fibers and glass fibers. The expanded material has more than about 55% by volume voids.

In a diaphragm 1, at a front surface side surface layer of a base material 10 made of pulps 20 which are mainly composed of cellulose, a mixed layer 11 in which the pulps 20, mica 22, and cellulose nanofibers 21 are mixed is formed.

A sound apparatus includes a piezoelectric device, a vibration member connected to the piezoelectric device, a first magnet connected to the piezoelectric device, and a second magnet facing the first magnet, which can readily realize a desired frequency characteristic.

Disclosed is a mid-range speaker. The operating range of the mid-range speaker can extend to 20 KHz, and the speaker has an improved high-frequency directivity. A mid-range speaker, comprising a basket, a diaphragm arranged on the basket, a magnetic circuit system arranged on the basket, and a voice coil connected to the diaphragm, wherein the diaphragm comprises a cellular board having a front face and a back face, and covering films respectively covering the front face and the back face of the cellular board; and the cellular board is provided with a plurality of holes.

In a diaphragm 1, at a front surface side surface layer of a base material 10 made of pulps 20 which are mainly composed of cellulose, a mixed layer 11 in which the pulps 20, mica 22, and cellulose nanofibers 21 are mixed is formed.

A sound apparatus includes a piezoelectric device, a vibration member connected to the piezoelectric device, a first magnet connected to the piezoelectric device, and a second magnet facing the first magnet, which can readily realize a desired frequency characteristic.

A speaker diaphragm includes a first lamination region and a second lamination region. In the first lamination region, a plurality of layers are laminated in a thickness direction of the speaker diaphragm. In the second lamination region, a plurality of layers different in number from the plurality of layers in the first lamination region are laminated. The second lamination region is different from first lamination region in average density.