An energy harvesting circuit is disclosed and comprises one or more electrical loads that consume direct current (DC) power, a rectifier, and a hybrid acoustic absorber. The rectifier comprises one or more active switching elements that are driven by a gate drive voltage. The hybrid acoustic absorber comprises a diaphragm and a voice coil. The diaphragm is constructed at least in part of a piezoelectric material. The piezoelectric material is configured to generate a diaphragm voltage in response to sound waves deforming the diaphragm. The diaphragm voltage is at least equal to the gate drive voltage to drive the one or more active switching elements of the rectifier. The voice coil is attached to the diaphragm and configured to generate a voice coil voltage that is less than the gate drive voltage of the one or more active switching elements.

A multi-input-driving loudspeaker, including: a frame; a cone arranged on the frame; a main input-driving mechanism; and a plurality of secondary input-driving mechanisms; wherein the main input-driving mechanism is arranged between the plurality of secondary input-driving mechanisms; the main input-driving mechanism includes a main voice coil, a T-yoke, and a front panel and a first magnetic steel sleeved on the T-yoke, a main voice coil mounting hole is provided in the middle of the cone, an upper end portion of the main voice coil is connected to the main voice coil mounting hole; each of the secondary input-driving mechanisms includes a secondary voice coil and a secondary magnetic circuit assembly formed with a secondary magnetic gap, a plurality of secondary voice coil mounting holes are correspondingly provided on the cone, an upper end portion of each secondary voice coil is connected to a corresponding secondary voice coil mounting hole.

Disclosed is a sound production device including a housing and a vibration assembly, the vibration assembly including a voice coil being of a hollow columnar structure and a vibration diaphragm bonded to an end face of the voice coil; where the sound production device further includes a system stabilization component bonded to an end face of the voice coil or to a side wall of the voice coil; the system stabilization component is of a line-like structure formed by winding a metal wire, and includes a first connection part connected to the voice coil, a deformation part, and a second connection part connected to the housing.

Disclosed is a sound production device including a housing and a vibration assembly, the vibration assembly including a voice coil being of a hollow columnar structure and a vibration diaphragm bonded to an end face of the voice coil; where the sound production device further includes a system stabilization component bonded to an end face of the voice coil or to a side wall of the voice coil; the system stabilization component is of a line-like structure formed by winding a metal wire, and includes a first connection part connected to the voice coil, a deformation part, and a second connection part connected to the housing.

A method for manufacturing an electrodynamic acoustic transducer is disclosed. The electrodynamic acoustic transducer comprises a frame and/or a housing, a membrane, at least one coil and a magnet system, wherein the coil, in a cross sectional view with a coil axis being part of the sectional plane, comprises a plurality of conductive layers formed by an electrical conductor of the coil. The electrical conductor has a rectangular cross section in said cross sectional view, wherein a longer side of the rectangular cross section is substantially perpendicular to the loop axis. According to this method, a stack of conductive layers is made from the electrical conductor by stacking of separate pieces of the electrical conductor and electrically connecting the stacked separate pieces and/or by folding of the electrical conductor.

A loudspeaker includes a diaphragm having a front surface facing in a forward direction for producing sound to be radiated outwardly from the loudspeaker in the forward direction and a back surface facing in a backward direction that is opposite to the forward direction; a magnet unit configured to provide magnetic field in a magnetic gap. The magnetic gap is located between a first portion of the magnet unit located radially inwards of the magnetic gap with respect to a longitudinal axis of the loudspeaker and a second portion of the magnet unit located radially outwards of the magnetic gap with respect to the longitudinal axis of the loudspeaker. A voice coil is configured to sit in the magnetic gap when the diaphragm is in a rest position.

An electrodynamic acoustic transducer, is disclosed, which comprises a frame and/or a housing, a membrane, at least one coil and a magnet system. The coil in a cross sectional view with a coil axis being part of the sectional plane comprises a plurality of conductive layers formed by an electrical conductor of the coil. The electrical conductor has a rectangular cross section in said cross sectional view, wherein a longer side of the rectangular cross section is substantially perpendicular to the loop axis. Furthermore, a method for manufacturing an electrodynamic acoustic transducer of the proposed kind is disclosed. According to this method, a stack of conductive layers is made from the electrical conductor by stacking of separate pieces of the electrical conductor and electrically connecting the stacked separate pieces and/or by folding of the electrical conductor.

A method for manufacturing an electrodynamic acoustic transducer is disclosed. The electrodynamic acoustic transducer comprises a frame and/or a housing, a membrane, at least one coil and a magnet system, wherein the coil, in a cross sectional view with a coil axis being part of the sectional plane, comprises a plurality of conductive layers formed by an electrical conductor of the coil. The electrical conductor has a rectangular cross section in said cross sectional view, wherein a longer side of the rectangular cross section is substantially perpendicular to the loop axis. According to this method, a stack of conductive layers is made from the electrical conductor by stacking of separate pieces of the electrical conductor and electrically connecting the stacked separate pieces and/or by folding of the electrical conductor.

An energy harvesting circuit is disclosed and comprises one or more electrical loads that consume direct current (DC) power, a rectifier, and a hybrid acoustic absorber. The rectifier comprises one or more active switching elements that are driven by a gate drive voltage. The hybrid acoustic absorber comprises a diaphragm and a voice coil. The diaphragm is constructed at least in part of a piezoelectric material. The piezoelectric material is configured to generate a diaphragm voltage in response to sound waves deforming the diaphragm. The diaphragm voltage is at least equal to the gate drive voltage to drive the one or more active switching elements of the rectifier. The voice coil is attached to the diaphragm and configured to generate a voice coil voltage that is less than the gate drive voltage of the one or more active switching elements.

There is provided a content presentation system, a content presentation device, and a wind presenting device which are suitable for content presentation by air blast. The content presentation system includes a control unit and a wind presenting device. The control unit generates a wind presentation drive signal on the basis of a predetermined trigger included in content. The wind presenting device includes a housing including an opening formed therein, a diaphragm supported by the housing, and a diaphragm drive mechanism that drives the diaphragm on the basis of the wind presentation drive signal, reduces a volume of a space formed by the housing and the diaphragm, and causes air in the space to blast from the opening.