Abstract: The present disclosure relates to an acoustic device. The acoustic device includes an enclosure and a speaker enclosed by the enclosure. The enclosure includes a magnesium based composite material. The magnesium based composite material includes a magnesium based metal matrix and nanoparticles dispersed therein. The present disclosure also relates to an earphone.

Abstract: The present disclosure relates to a magnesium based composite material. The magnesium based composite material includes a magnesium based metal matrix and nanoparticles dispersed in the magnesium based metal matrix in a weight percentage of a range from about 0.01% to about 2%. The present disclosure also relates to a method for making the magnesium based composite material. In the method, the nanoparticles are added to the magnesium based metal at a temperature of about 460° C. to about 580° C. to form a mixture. The mixture is ultrasonically vibrated at a temperature of about 620° C. to about 650° C. The mixture is casted at a temperature of about 650° C. to about 680° C., to form an ingot.

Abstract: An exemplary earphone unit includes an earphone, a plug, a box, and a lead. The lead includes a first section and a second section separate from the first section. The box includes a housing defining a first opening and a second opening, a disk mounted in the housing, a shaft fixed in the housing, a sleeve surrounding the shaft, and a spring connecting the shaft with the sleeve. The sleeve is rotatably disposed on the disk via two balls. The first section of the lead extends through the first opening to connect the plug with the disk. The second section is wound around the sleeve. The second section has one end fixed to the sleeve, and an opposite end extending through the second opening to connect the earphone. The spring accumulates elastic potential energy when the spring is pulled by the second section of the lead away from the sleeve.

Abstract: An exemplary earphone set includes a shell, a speaker received in the shell, and an in-ear cap and an in-concha cap. The shell includes a sound tube having a first locking structure formed on an outer circumferential wall thereof. Each of the in-ear cap and the in-concha cap includes an inner tube having a second locking structure formed on an inner circumferential wall thereof, and a casing extending from a front end of the inner tube towards the shell. The first locking structure is detachably lockable with the second locking structure of one of the in-ear cap and the in-concha cap as selected by a user.

Abstract: An exemplary loudspeaker includes a frame, a yoke engaged with the frame, a magnet fixed to the yoke, a magnet fixed inside the yoke, a diaphragm attached to the frame, and a voice coil attached to the diaphragm. The frame includes a flange and a supporting bracket. The flange includes two parallel straight portions and two curve portions connected between the two parallel straight portions respectively. The supporting bracket includes a main body, two first extending portions extending from the main body and fixed to the straight portions, two second extending portions extending from the main body and fixed to the curve portions, and a through hole defined in a center of the main body. The yoke is received in the through hole of the main body.

Abstract: An exemplary loudspeaker includes a frame, a yoke engaged with the frame, a magnet fixed to the yoke, a magnet fixed to the yoke, a diaphragm attached to the frame, and a voice coil attached to the diaphragm. The frame includes an annular flange and a supporting bracket. The supporting bracket includes two mounting portions respectively extending down from opposite sides of the annular flange and an annular connecting portion located between the two mounting portions. The yoke is embedded in the annular connecting portion.

Abstract: An electronic device includes an enclosure and a speaker set received in the enclosure. The speaker set includes a shell, a pair of first and second speakers received in the shell. The first speakers provide high frequency acoustic output, and the second speakers provide low and middle frequency acoustic output. The shell includes a fixing plate. The fixing plate defines two tweet outlets aligning respectively with the first speakers, and two middle woof outlets aligning respectively with the second speakers. A central point of each middle woof outlet is located nearer to an imaginary central line of the fixing plate than a central point of each tweet outlet. A portion of each of the middle woof outlets is shaded by a portion of the electronic device. The tweet outlets are located beside the portion of the electronic device but not shaded by the portion.

Abstract: An exemplary speaker set includes a shell and a speaker. The shell includes a bottom cover and a top cover engaging with the bottom cover. The bottom cover and the top cover cooperatively define a resonance chamber therebetween. The bottom cover defines a through hole therein. The top cover defines a mounting hole corresponding to and communicating with the through hole. The speaker includes a vibration part and a magnetic part driving the vibration part. The vibration part is inserted the mounting hole and engages with the top cover. The magnetic part is inserted the through hole and intimately engages with the bottom cover.

Abstract: An exemplary display includes a front frame, a rear frame, a screen sandwiched between the front frame and the rear frame, and two sound boxes received between the front frame and the rear frame. Two openings are defined in a bottom of the display. Each sound box includes a front cover, a rear cover, and a woofer and two tweeters mounted in the front cover. The woofer faces a front and a corresponding opening of the display. The tweeters face the corresponding opening of the display.

Abstract: An exemplary earphone module includes a faceplate, a bottom cover connected to the top cover, and a microphone received between the faceplate and the bottom cover. The faceplate defines a sound hole therein. The microphone defines a Helmholtz resonance chamber therein. A washer is placed between the faceplate and the microphone. The washer has a sound chamber communicating the sound hole with the Helmholtz resonance chamber. The Helmholtz resonance chamber has a volume V, the sound hole has a diameter d and a length l, and the sound chamber has a diameter D. The diameter D of the sound chamber meets the equation D=d or the formula D ? 4 ? V ? ? ( l + 0.8 ? d ) .