EMFi in wearable audio applications

Flexible microphone and earphone prototypes for wearable applications were developed by using ElectroMechanical Film (EMFi). A suitable application for the developed headset can be, for instance, as accessory of rescue services or sport enthusiasts. Due its versatile properties, EMFi can be used both as microphone and earphone material. The sensor operation is based on thickness changes caused by an external force or pressure, generating charge and thus voltage on the electrodes. EMFi also works conversely, converting electrical energy to vibration and hence functioning as an actuator. In addition, measurement electronics for the microphone and earphone were implemented. Preliminary test measurements were carried out: the frequency response of the EMFi microphone was compared with the one of a reference B&K microphone. The EMFi microphone provides rather good response. Also subjective listening tests were done. For these measurements, the EMFi headset was integrated inside a neoprene hood used by the surface rescuers. Both with the microphone and earphone the quality of voice was sufficient. Based on the results, EMFi seems to be a promising material for some wearable audio applications. Keywords— EMFi, film, microphone, earphone.