title: Spectral pattern complexity analysis and the quantification of voice normality in healthy and radiotherapy patient groups.
abstract: Vocal fold functionality may alter in response to direct radiotherapy or indirectly by perturbation of the hypothalamic-pituitary axis. Perceptual assessment of voice quality is difficult to summarise in a single, reliable figure of normality and normality itself is undefined. In this study spectral analysis of vocal fold vibration, based on impedance variations measured across the larynx using an electro-glottogram, is used to build a single parameter description of standard vowel phonation in the normal male population. Patient data and perceptual assessment are then compared to this standard. The spectral pattern of the vowel/i/ electro-glottogram time series is analysed using approximate entropy after dynamic fundamental-harmonic frequency normalisation. The approximate entropy provides a single estimate of the spectral pattern complexity. A cohort of 89 normal males formed two statistically distinct groups, G1, with strong spectral pattern and high complexity 0.338 (+/-0.036), and G2 with a weak spectral pattern and low complexity 0.175 (+/-0.049). Membership ratio G1:G2 was 2:1. A cohort of 30 male larynx cancer cases were analysed approximately 3-6 months after irradiation, and three male prophylactic cranial irradiation cases some years after treatment. Two-thirds of patients had G2 or lower levels of complexity. The lower G2 complexity level appears to be the subjective, as well as the objective, threshold for voice normality.
authors.affiliation: North Western Medical Physics, Christie Hospital NHS Trust, Wilmslow Road, Withington, Manchester M20 4BX, UK. chris.moore@physics.cr.man.ac.uk
authors.forename: Christopher
authors.initials: C
authors.lastname: Moore
authors.forename: Kathiresan
authors.initials: K
authors.lastname: Manickam
authors.forename: Terry
authors.initials: T
authors.lastname: Willard
authors.forename: Susan
authors.initials: S
authors.lastname: Jones
authors.forename: Nicholas
authors.initials: N
authors.lastname: Slevin
authors.forename: Steven
authors.initials: S
authors.lastname: Shalet
mesh_terms: D000465:Algorithms; D015331:Cohort Studies; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D005931:Glottis / Q000503:physiopathology / Q000528:radiation effects; D006801:Humans; D007822:Laryngeal Neoplasms / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology / Q000532:radiotherapy*; D007830:Larynx / Q000503:physiopathology / Q000528:radiation effects; D008297:Male; D010992:Plethysmography, Impedance / Q000379:methods*; D011878:Radiotherapy / Q000009:adverse effects; D020127:Recovery of Function / Q000502:physiology / Q000528:radiation effects; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013018:Sound Spectrography / Q000379:methods*; D013064:Speech Disorders / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D013068:Speech Production Measurement / Q000379:methods*