Kalimba Inspired Metastructure for Frequency Selectivity

Abstract In this study, the frequency selectivity phenomenon in the mammalian cochlea is replicated in a simulated environment. Frequency selectivity is found to be of crucial importance in the accurate perception of environmental noise. Previous studies have found that mammalian cochlea consists of basilar membrane which varies in width and stiffness along its length. This results in a gradient in mechanical properties and in turn results in a place-coding mechanism, where different frequencies of sound cause maximum displacement of the basilar membrane at specific locations along its length. The basilar membrane consists of multiple hair cells located along its length. The displacement of the basilar membrane due to sound waves causes hair cells to bend. This bending of hair cells activates ion channels, leading to the generation of electrical signals. Leveraging the principles of cochlear processing, a Kalimba-key-based broadband vibroacoustic device is developed in this study having potential implications for sensory technology and human perception enhancement. Dynamic vibration resonators (DVRs) are employed in this research to emulate the frequency-selective behavior of the mammalian cochlea where the DVRs act as hair cells. A beam structure, acting as a platform for 136 strategically placed DVRs, each corresponding to a Kalimba instrument key is considered. Upon stimulation, these Kalimba keys replicate the vibrations of the cochlear basilar membrane, enabling the recreation of frequency selectivity across a broad spectrum. To simulate the system, a Timoshenko beam is considered to consist of spatially attached Kalimba keys modeled as a Single-Degree Of Freedom (SDOF) systems. A Finite Element (FE) model of this system is developed to calculate the response of the system. Frequency selectivity for different combinations of Kalimba keys is explored in this study. This study shows promising results having potential implications extending beyond healthcare, encompassing fields such as robotics where the integration of biological cochlear principles could enhance robots’ sensory perception and interaction capabilities in diverse environments.