Investigation of a new method for sound generation – Advanced Digital Sound Reconstruction

Abstract

The current loudspeaker market has a high demand for portable audio devices. Hence, the miniaturization of loudspeakers (microspeakers) is of great importance for manufacturers. Traditional loudspeakers – for example the electrodynamic loudspeaker – are the forerunners, but so-called MEMS loudspeakers (Micro-Electro-Mechanical-System) have emerged recently. MEMS devices have already been used for sensors (i.e., microphones) to a great extend due to their advantages regarding form factor and production efficiency. Albeit additional challenges for actuators like moving enough air with a microstructure – as it is the case for a loudspeaker – the usage of MEMS technology for loudspeakers is very attractive.Since especially low-frequency audio signals often pose problems for microspeakers, this article focuses on a new sound generation technique called Advanced Digital Sound Reconstruction (ADSR) which is especially well-suited for low-frequency audio signals since ADSR can generate more volume displacement relative to its size. Based on a general description of the principle, an outlook of the possibilities regarding achievable sound pressure compared to the classical excitation scheme is derived. Furthermore, measurements are presented, which aim to prove the concept of ADSR based on already existing actuators.

MEMS audio speakers *

“…However, these are not yet widely found in the market. In line with the idea of DSR, a recent publication [117] discusses a design alterationadvanced digital signal reconstruction. It has a redirection unit that splits positive and negative sound pulses.…”

Modeling and numerical simulations of MEMS shutter devices

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We investigate the acoustic behaviour of Micro-Electro-Mechanical-Systems (MEMS) with a focus on shutter devices. These shutter devices can be used for a new method of sound generation -which we call Advanced Digital Sound Reconstruction (ADSR) -where a redirection mechanism for sound pulses is incorporated [1]. With the help of this redirection mechanism, sound pulses can be generated which are superimposed to form an audio signal.

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