Evaluation of Neuromorphic Spike Encoding of Sound Using Information Theory

TL;DR

This paper introduces an information-theoretic framework to quantitatively evaluate and compare the efficiency of different spike encoding algorithms for sound, highlighting the superior performance of Leaky Integrate-and-Fire coding.

Contribution

It provides a systematic, quantitative method to assess spike encoding algorithms using information theory, which was lacking in prior research.

Findings

Leaky Integrate-and-Fire coding has the highest coding efficiency.

Disparities exist among different encoding algorithms.

The framework offers insights into encoding complex sound stimuli.

Abstract

The problem of spike encoding of sound consists in transforming a sound waveform into spikes. It is of interest in many domains, including the development of audio-based spiking neural networks, where it is the first and most crucial stage of processing. Many algorithms have been proposed to perform spike encoding of sound. However, a systematic approach to quantitatively evaluate their performance is currently lacking. We propose the use of an information-theoretic framework to solve this problem. Specifically, we evaluate the coding efficiency of four spike encoding algorithms on two coding tasks that consist of coding the fundamental characteristics of sound: frequency and amplitude. The algorithms investigated are: Independent Spike Coding, Send-on-Delta coding, Ben's Spiker Algorithm, and Leaky Integrate-and-Fire coding. Using the tools of information theory, we estimate the information that the spikes carry on relevant aspects of an input stimulus. We find disparities in the coding efficiencies of the algorithms, where Leaky Integrate-and-Fire coding performs best. The information-theoretic analysis of their performance on these coding tasks provides insight on the encoding of richer and more complex sound stimuli.