Acoustic analysis and design of miniature loudspeakers for mobile phones

Abstract

Miniature loudspeakers are key components of mobile phones in modern-day wireless communication. Although the fundamental principle of miniature loudspeakers is similar to that of larger loudspeakers of other kinds, there are still some distinct features of these devices that may give rise to different design considerations. An extensive electroacoustic analysis is conducted to explore the characteristics of miniature loudspeakers when fitted to the interior of mobile phones. Of particular interest is the modeling of the duct structure in the analysis. Thiele and Small parameters of miniature loudspeakers are experimentally identified. Dynamic response simulation is carried out on the basis of electro-mechano-acoustical (EMA) equivalent circuits. Head diffraction in hands-free application is also simulated. In order to assess the miniature loudspeakers, performance indices including frequency response, sensitivity, and efficiency are measured. An acoustic design that extends the low-frequency bandwidth is also presented to meet the ever-increasing demand of sound quality of miniature loudspeakers.