Citation: Alalayah, K.M.; Senan, E.M.; Atlam, H.F.; Ahmed, I.A.; Shatnawi, H.S.A. Automatic and Early Detection of Parkinson’s Disease by Analyzing Acoustic Signals Using Classification Algorithms Based on Recursive Feature Elimination Method. Diagnostics 2023, 13, 1924. https://doi.org/10.3390/ diagnostics13111924 Academic Editor: Mehedi Masud Received: 11 May 2023 Revised: 23 May 2023 Accepted: 27 May 2023 Published: 31 May 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). diagnostics Article Automatic and Early Detection of Parkinson’s Disease by Analyzing Acoustic Signals Using Classification Algorithms Based on Recursive Feature Elimination Method Khaled M. Alalayah 1, * , Ebrahim Mohammed Senan 2, * , Hany F. Atlam 3 , Ibrahim Abdulrab Ahmed 4 and Hamzeh Salameh Ahmad Shatnawi 4 1 Department of Computer Science, Faculty of Science and Arts, Najran University, Sharurah 68341, Saudi Arabia 2 Department of Artificial Intelligence, Faculty of Computer Science and Information Technology, Alrazi University, Sana’a, Yemen 3 Cyber Security Centre, WMG, University of Warwick, Coventry CV4 7AL, UK; hany.atlam@warwick.ac.uk 4 Computer Department, Applied College, Najran University, Najran 66462, Saudi Arabia; iaalqubati@nu.edu.sa (I.A.A.); hsshatnawi@nu.edu.sa (H.S.A.S.) * Correspondence: kmalalayah@nu.edu.sa (K.M.A.); senan26102020@gmail.com (E.M.S.) Abstract: Parkinson’s disease (PD) is a neurodegenerative condition generated by the dysfunction of brain cells and their 60–80% inability to produce dopamine, an organic chemical responsible for controlling a person’s movement. This condition causes PD symptoms to appear. Diagnosis involves many physical and psychological tests and specialist examinations of the patient’s nervous system, which causes several issues. The methodology method of early diagnosis of PD is based on analysing voice disorders. This method extracts a set of features from a recording of the person’s voice. Then machine-learning (ML) methods are used to analyse and diagnose the recorded voice to distinguish Parkinson’s cases from healthy ones. This paper proposes novel techniques to optimize the techniques for early diagnosis of PD by evaluating selected features and hyperparameter tuning of ML algorithms for diagnosing PD based on voice disorders. The dataset was balanced by the synthetic minority oversampling technique (SMOTE) and features were arranged according to their contribution to the target characteristic by the recursive feature elimination (RFE) algorithm. We applied two algorithms, t-distributed stochastic neighbour embedding (t-SNE) and principal component analysis (PCA), to reduce the dimensions of the dataset. Both t-SNE and PCA finally fed the resulting features into the classifiers support-vector machine (SVM), K-nearest neighbours (KNN), decision tree (DT), random forest (RF), and multilayer perception (MLP). Experimental results proved that the proposed techniques were superior to existing studies in which RF with the t-SNE algorithm yielded an accuracy of 97%, precision of 96.50%, recall of 94%, and F1-score of 95%. In addition, MLP with the PCA algorithm yielded an accuracy of 98%, precision of 97.66%, recall of 96%, and F1-score of 96.66%. Keywords: Parkinson’s disease; exploratory data analysis; coefficient of variation; t-SNE; REF; machine learning 1. Introduction Parkinson’s disease (PD) is a neurodegenerative disease caused by the death of neu- rons (called substantia nigra) that generate dopamine [1]. Dopamine is an organic chemical of the catecholamine and phenethylamine families that controls physical movement by transmitting messages between the brain and the substantia nigra, thereby enabling co- ordinated movement [2]. When 60–80% of the cells that produce dopamine are lost, the amount of dopamine is not enough to control a person’s movements and, thus, symptoms of PD appear [3]. The lack of dopamine neuron production leads to losing control over the Diagnostics 2023, 13, 1924. https://doi.org/10.3390/diagnostics13111924 https://www.mdpi.com/journal/diagnostics