The performance of a miniature loudspeaker used in computer, communication, and consumer electronics products is an integrated function with coupled magnetic, electrical, mechanical, and acoustical fields. Through the finite element method, optimal design parameters to enhance the performance of a miniature loudspeaker are obtained. The sound pressure response of the miniature loudspeaker is simulated by using an equivalent circuit method. Its electrical driver, mechanical motion, and acoustical radiation are analogized by their equivalent elements individually. For the present work, such an analysis is carried out for a miniature loudspeaker manufactured in the cellular phone industry. All speaker parameters in the analysis are experimentally measured. Sound pressure responses are experimentally taken by PULSE Electroacoustics in an anechoic chamber. The equivalent-circuit analysis show fairly good agreement with the experimental results.

This paper presents a microelectromechanical system (MEMS) capacitive microphone fabricated by using a combination of surface and bulk micromachining techniques equipped with favorable integrated complementary metal-oxide semiconductor capability. Through the proposed equivalent circuit model for the packaged microphone, optimal diaphragm diameter, diaphragm thickness, backplate height, air gap, front chamber volume, back chamber height, and acoustic hole fraction have been determined by analyzing and simulating the capacitive microphone. Consequently, this design model can optimize choice of materials, microphone size, and microphone performance. All parameters for the analysis have been experimentally measured for the microphone. To verify our analysis, the microphone sensitivity has been experimentally measured by pulse electroacoustics with the software SOUND CHECK in an anechoic box. The simulation and experimental results for sensitivity of the microphone follow each other within a range of 2 dB. Moreover, the measured specifications indicate that the packaged microphone has notably high sensitivity (−42±3 dB V/Pa at 1 kHz), low power consumption (<250 μA), high S/N ratio (>55), and low distortion (<0.5%).

A single-chip micromachined microphone is proposed to meet the requirement of small size, high performance, and low cost. It consists of a rigid perforated backplate, a floating diaphragm, air gaps, an acoustic chamber, and a silicon substrate. The simply supported diaphragm can be achieved by using two sacrificial layers. The sacrificial material is phosphor-silicate glass, and sacrificial layers are etched away to form the air gaps. The KOH etching solution is used to fabricate the acoustic chamber in pyramidal shape. The simply supported diaphragm has the larger mechanical compliance than that of clamped diaphragm. The electro-acoustical sensitivity of the simply supported structure has at least 5.72 times larger than that of clamped structure. Although there are many parameters can increase electroacoustical sensitivity, the simply supported diaphragm is one of the most effective approaches. Bias voltage can be used to increase sensitivity, and it creates the electrostatic force on the diaphragm. The dominative parameter of diaphragm deflections changes from sound pressure to the electrostatic force, when bias voltage is larger than 2.3 V. A microbeam is used to support a floating diaphragm, and the microbeam determines the resonance modes. The natural resonance frequency should locate outside the telephony band. When the width of the microbeam is small, the lateral vibration will appear early and result in the natural resonance frequency.

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