Creating a Flat Flexible Microphone Array

Abstract

In this study, we created and characterized three types of microphones using the piezoelectric properties of Em t, a polymer, and two types of macro- ber composite sensors (MFCs). We also successfully achieved sound source separation using an array of these microphones. The main advantages of these microphones over commercially available microphones are their flexibility and thin form factors while they outperform other piezoelectric microphones due to their ability to lie at against a surface with similar sensitivity. In our characterization of the microphones, we found the Em t sensors to be unreliable, likely due to their lack of durability and the difficulty we had in applying consistent, conductive electrodes to the bare material. When using the MFC microphones, we found that they had frequency responses that peaked at frequencies corresponding to the most sensitive range of human hearing, with lower sensitivities at lower frequencies. The sensitivity was still high enough to easily record a human speaker within the same room. Linearity tests revealed large levels of total harmonic distortion (THD) at frequencies which were not sensitivity peaks. Although distortion was small at the sensitivity peaks, this significant non-peak distortion makes the microphones undesirable for high-quality applications. However, the microphones were shown to work with applications not requiring very high-quality sound, such as source separation. An array of microphones was constructed and we were able to effectively isolate the speech of two speakers who were speaking at the same time in a conference room.