title: A novel method for early diagnosis of Alzheimer's disease based on higher-order spectral estimation of spontaneous speech signals.
abstract: One main challenge for medical investigators is the early diagnosis of Alzheimer's disease (AD) because it provides greater opportunities for patients to be eligible for more clinical trials. In this study, higher order spectra of human speech signals during AD were explored to analyze and compare the quadratic phase coupling of spontaneous speech signals for healthy and AD subjects using bispectrum and bicoherence. The results showed that the quadratic phase couplings of spontaneous speech signal of persons with Alzheimer's were reduced compared to healthy subject. However, the speech phase coupled harmonics shifted to the higher frequencies in Alzheimer's than healthy subjects. In addition, it was shown not only are there significant differences between Alzheimer's and control subjects in parameters estimated, but also the speech patterns appeared to have fluctuated in both types of spontaneous speech.
authors.affiliation: Department of Biomedical Engineering, Hakim Sabzevari University, Sabzevar, Iran.
authors.forename: Mahda
authors.initials: M
authors.lastname: Nasrolahzadeh
authors.affiliation: Department of Biomedical Engineering, Hakim Sabzevari University, Sabzevar, Iran.
authors.forename: Zeynab
authors.initials: Z
authors.lastname: Mohammadpoory
authors.affiliation: Department of Biomedical Engineering, Hakim Sabzevari University, Sabzevar, Iran.
authors.forename: Javad
authors.initials: J
authors.lastname: Haddadnia
keywords: Alzheimer’s disease; Bicoherence estimation; Bispectrum estimation; Phase coupling; Spontaneous speech signal