Numerical study on magneto-acoustic thermal characteristics of micro-speaker for mobile phones

Abstract The numerical study was conducted on 1.2 W micro-speaker module of yoke thickness 0.40 mm without center air hole used in mobile phones and experimentally validated for sound pressure level and temperature distribution within ± 5.9% and ± 3.6%, respectively for frequency ranging from 100 Hz to 20 kHz. The sound pressure level, magnetic flux density, magnetic excitation force and temperature distribution of three different micro-speaker designs were evaluated. The micro-speaker module design with yoke thickness of 0.45 mm without center air hole showed superior acoustic, magnetic and thermal performance as compared to other module designs with the lowest voice coil temperature of 126.02 °C and the maximum sound pressure level of 118.6 dB around resonant frequency of 1100 Hz. The proposed nonlinear thermal model predicted the voice coil temperature accurately. In addition, the present study demonstrated the complete 3-dimensional thermal distribution of micro-speaker components and the detailed heat flow pattern.