Spectral noise estimation in the evaluation of pathological voice
Logopedics Phoniatrics Vocology 31(4): 182-189
A measure of the harmonics-to-noise ratio (HNR) in voice signals is used for assisting in the classification of voice pathologies. HNR estimation for voice signals has been investigated using time domain, cepstral, Fourier series and Fourier transform analyses. The present investigation focuses on methods that use a direct application of the Fourier transform to the signal. Three approaches to obtaining a HNR index from the power spectrum are reviewed. The present study uses synthetic voice signals to provide an unambiguous assessment of methods. The study highlights the fact that even though the indices derived from the power spectrum are useful in separating pathological and normal voice data sets, they provide only indirect information regarding the HNR of the glottal signal.