Issue N# 4 - 1999
Value of the relative phonetogram (RP) for voice assessment
Authors : C. Hilgenheger, J. Sarfati, E. Reyt, C. Sittel, H. E. Eckel (Köln)
Ref. : Rev Laryngol Otol Rhinol. 1999;120,4:231-238.
Article published in french
The phonetogram in a recognized element of voice evaluation, but its relation to perceptual voice quality is unclarified. The phonetograms area is easy to mesure since the existence of efficient computer software. So information about frequency and intensity range can be united in one single parameter. The individual phonetogram area in relation to a gender- and training-specific normal value constitutes the "relative phonetogram (RP)".
A prospective evaluation of the relative phonetogram was performed by means of a statistical analysis of its correlation to perceptual voice assessment (grade/rough/breathy) and to maximal phonation time. The acoustic parameters jitter, shimmer, SNR were examined in the same way, to allow for comparison of the RP's importance with the importance of common "objective" features in the identic group of patients. 114 patients with two subsets are included : 61 patients after partial laryngectomy (laser or conventional surgery), 53 patients with différent glottic pathologies. The perceptive evaluation was done by a trained jury of an ENT-specialist and a speech therapist. The phonetogram and the maximal phonation time were measured by a trained medical student with regard of the examination references publicated by the Union of European Phoniatrics. The computer software for area measurement was MSImageProPlus, the one for sound analysis was Dr. Speech (Tiger Electronics). Statistical program : SPSS 8.0.
Results : the comparison between the two subsets of patients shows lower RPs for partial laryngectomy than for other patients in all degrees of hoarseness. In both subsets there is a correlation between RP and hoarseness values : the average values of RP differ significantly in dependence of grande. This is even more marked for the patients after laryngeal surgery. Furthermore high RPs are only present in patients with (relativly) high maximal phonation time, and mean RP correlates with maximal phonation time. A correlation between the parameters of sound analysis and the score of "grade" exists, but is not as marked as for the RP.
Conclusion : the significance of the RP's mean value for subsets of 15-20 patients has been demonstrated. It is justified to interpret a certain variance of this parameter as difference in the degreee of hoarseness. In this context, the importance of the mean RP is higher than the importance of jitter, shimmer, SNR (when measured with the above mentioned computer program, which allows no evaluation of parameter combinations). Therefore this parameter could be interesting for comparisions of dysphonic patients, for instance after glottic cancer treatment.