# Comparison of echo state network output layer classification methods on noisy data

**Authors:** Ashley Prater  
**arXiv:** [1703.04496](https://arxiv.org/abs/1703.04496)  
**Date:** 2017-03-13  
**Summary page:** https://www.summarizepaper.com/en/paper/1703.04496v1/

## Key points

- Study conducted by Ashley Prater on classifying noisy data using echo state networks (ESNs)
- ESNs are recurrent neural networks used for processing spatiotemporal data
- ESNs have gained popularity in speech recognition, event detection, and robot control
- ESNs train the output layer using linear readout weights through a least squares approach
- However, this method may not be accurate with noisy data
- Three methods compared for training the output layer: trained linear weights, sparse trained linear weights, and trained low-rank approximations of reservoir states
- Experiments conducted on synthetic and natural datasets to evaluate performance
- Regularized least squares superior for low noise levels, while low-rank approximations improve accuracy with higher noise levels
- Study provides insights into improving ESN performance with noisy data

## Summary

This study, conducted by Ashley Prater, focuses on the performance of different methods for classifying noisy data using echo state networks (ESNs). ESNs are a type of recurrent neural network where the internal layer has fixed random weights and only the output layer is trained on specific data. They have gained popularity in processing spatiotemporal data in real-world applications such as speech recognition, event detection, and robot control. The strength of ESNs lies in their simple method for training the output layer, which typically involves finding linear readout weights using a least squares approach. However, this method may not yield satisfactory accuracy when dealing with noisy data. To address this issue, the study compares three different methods for training the output layer of ESNs: using trained linear weights, using sparse trained linear weights, and using trained low-rank approximations of reservoir states. The experiments were conducted on both synthetic and natural datasets to evaluate the performance of each method. The results suggest that using regularized least squares to train linear output weights is superior when dealing with low noise levels. However, when datasets are contaminated with higher levels of noise utilizing low-rank approximations can significantly improve classification accuracy. Overall, this study provides valuable insights into improving the performance of ESNs in handling noisy data by comparing different methods for training the output layer. These findings can be beneficial for researchers and practitioners working with ESNs in various real-world applications.