Abstract: An acoustic device includes a first sound producing component and a back cavity structure. The first sound producing component has a first front side and a first back side, wherein the first sound producing component is a high frequency sound unit, and the first front side faces a sound propagating opening of the acoustic device. The back cavity structure is connected to the first back side of the first sound producing component. The first sound producing component produces a first acoustic wave from the first front side towards the sound propagating opening, and the first sound producing component produces a second acoustic wave from the first back side towards a back cavity of the back cavity structure. The back cavity structure is configured to flatten a peak or a dip of a frequency response of the first sound producing component.

Abstract: An acoustic device includes a first sound producing component and a back cavity structure. The first sound producing component has a first front side and a first back side, wherein the first sound producing component is a high frequency sound unit, and the first front side faces a sound propagating opening of the acoustic device. The back cavity structure is connected to the first back side of the first sound producing component. The first sound producing component produces a first acoustic wave from the first front side towards the sound propagating opening, and the first sound producing component produces a second acoustic wave from the first back side towards a back cavity of the back cavity structure. The back cavity structure is configured to flatten a peak or a dip of a frequency response of the first sound producing component.

Abstract: A venting device includes a first flap, which is configured to be actuated to swing upward during a rising time, and a second flap, which is disposed opposite to the first flap and configured to be actuated to swing downward during a falling time, a first actuating portion disposed on the first flap, and a second actuating portion disposed on the second flap. The venting device configured to form a vent is disposed within a wearable sound device or to be disposed within the wearable sound device. The vent is formed via applying a first voltage to the first actuating portion and applying a second voltage on the second actuating portion, such that the venting device gradually forms the vent.

Abstract: A cell includes a membrane and an actuating layer. The membrane includes a first membrane subpart and a second membrane subpart, wherein the first membrane subpart and the second membrane subpart are opposite to each other. The actuating layer is disposed on the first membrane subpart and the second membrane subpart. The first membrane subpart includes a first anchored edge which is fully or partially anchored, and edges of the first membrane subpart other than the first anchored edge are non-anchored. The second membrane subpart includes a second anchored edge which is fully or partially anchored, and edges of the second membrane subpart other than the second anchored edge are non-anchored.

Abstract: An embossing machine includes a frame, a top magnet, die disk, and a bottom magnet. The top magnet has a top die cavity, a fixed hook, a handle and a bracket on the upper portion, and a bottom die cavity in the lower portion, wherein the top die cavity has a step circular surface which has a plurality of sliced screw holes formed in the top circumference and has a first elastic element disposed therein. The top magnet attracts a top die engaged with the top die cavity through a key and a key way formed thereof, wherein the top magnet has a bolt fixed therein and a second elastic element disposed inside. The die disk is engaged with the bolt on the top magnet, wherein the die disk has a gear fixed thereon and a plurality of sliced screw holes formed on the circumference for engaging with the top die cavity. The die disk further has an adjusting bolt which has a thorough opening therein to engage with the bolt on the top magnet, wherein the adjusting bolt has a bushing, a washer and a screw disposed at one end.