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Abstract
Most contemporary high-end microphones are dynamic microphones, adopting the most basic electromagnetic transduction principles. This study investigated the diaphragm structures of dynamic microphones. The diaphragms were composed of polyimide material, and the boundary settings required for actual operation were provided using finite element model analysis software. The characteristic frequencies caused by grooving variations on the three-dimensional diaphragm were analyzed for the various groove shapes and number. The groove angles and width variations were examined based on the optimal groove shape selected in the aforementioned analysis, and the effects of these shapes were determined based on the analytical results. Acoustic waves cause thin films to vibrate, forming the working principle behind dynamic microphones. The thin film drives a coil to vibrate in a magnetic field and cuts the line of magnetic force, subsequently producing a voltage on both ends of the coil. This audio-frequency-inducted voltage represents an acoustic wave message. The finite element model analysis software was used to conduct electromagnetic induction simulations; the sound source was fed to the diaphragm to drive the coil. The coil vibrations caused the line of magnetic force to be cut, and the final voltages produced were examined and compared.
Keywords
Acoustics, computer-assisted engineering, finite element analysis, vibration and acoustics, sound
Date received: 20 February 2015; accepted: 21 June 2015
Academic Editor: Lus Godinho
Introduction
Microphones, which are commonly known as mics (or mikes), and receivers are transducers that convert acoustic signals into electrical signals.1,2 The gramophone receiver that Edison invented in 1878 was the earliest microphone prototype. The history of the microphone can be traced to the end of the 19th century, when scientists, such as Alexander Graham Bell, searched for a favorable method to receive audio signals and enhanced the latest invention at the time, the telephone. During this period, scientists also invented the liquid and carbon microphones; however, these systems were barely usable.
In 1949, the DM4-type microphone was developed at the Wennebostel Laboratory (predecessor of the Sennheiser Laboratory) as the first feedback-suppressed, noise-compensated microphone. In 1961, Sennheiser released the MK102- and MK103type microphones at the Hannover Industrial Fair in Germany. These two models represented a new concept for microphone fabrication: adopting compact, thin, and lightweight vibration films that guaranteed exceptional audio quality. In 1978,...