Real-time FPGA implementation of a neuromorphic pitch detection system
This thesis explores the real-time implementation of a biologically inspired pitch detection system in digital electronics. Pitch detection is well understood and has been shown to occur in the initial stages of the auditory brainstem. By building such a system in digital hardware we can prove the feasibility of implementing neuromorphic systems using digital technology. This research not only aims to prove that such an implementation is possible but to investigate ways of achieving efficient and effective designs. We aim to achieve this complexity reduction while maintaining the fine granularity of the signal processing inherent in neural systems. By producing an efficient design we present the possibility of implementing the system within the available resources, thus producing a demonstrable system. This thesis presents a review of computational models of all the components within the pitch detection system. The review also identifies key issues relating to the efficient implementation and development of the pitch detection system. Four investigations are presented to address these issues for optimal neuromorphic designs of neuromorphic systems. The first investigation aims to produce the first-ever digital hardware implementation of the inner hair cell. The second investigation develops simplified models of the auditory nerve and the coincidence cell. The third investigation aims to reduce the most complex stage of the system, the stellate chopper cell array. Finally, we investigate implementing a large portion of the pitch detection system in hardware. The results contained in this thesis enable us to understand the feasibility of implementing such systems in real-time digital hardware. This knowledge may help researchers to make design decisions within the field of digital neuromorphic systems.