title: Clinical relevance of the fractal dimension of F0 perturbations computed by the box-counting method.
abstract: The box-counting method for determining the fractal dimension (Dfj) was applied to the fundamental frequency (F0) perturbations in normal and pathological voices in order to assess its clinical value. The upper limit of these Dfj values was similar for both groups, but the distribution for pathological voices extended to lower values than for the normal voices. However, these lower values were most probably the result of one or a few outlying frequency points due to incorrect determination of the vocal period. The Dfj of normal voices were within the range of values found for randomly varying F0 values. It was concluded, that the vocal perturbations in pathological voices are also more or less randomly distributed. So, the Dfj, at that least determined with the box-counting method, do not contain clinically relevant information in addition to the traditional measures for the extent of the vocal period perturbations. An exception is special perturbation types like diplophonia. The result of the computation is very sensitive for voice breaks and vibrato and depends on the number of periods.
authors.affiliation: The Institute of Phoniatrics, University Utrecht, The Netherlands.
authors.forename: W
authors.initials: W
authors.lastname: Boek
authors.forename: G H
authors.initials: GH
authors.lastname: Wieneke
authors.forename: P H
authors.initials: PH
authors.lastname: Dejonckere
mesh_terms: D001330:Electronic Data Processing; D005260:Female; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D013068:Speech Production Measurement; D013997:Time Factors; D014832:Voice Disorders / Q000175:diagnosis*; D014833:Voice Quality / Q000502:physiology