[The variability of the basic speech tone frequency in the patients presenting with functional voice disorders].

The objective of this study was to elucidate changes in tone sigma (σ) before and after the treatment of the patients with mutational falsetto (n=10) and functional dysphonia (n=10). The control group was comprised of 30 healthy subjects. A personal computer was used to determine the values of SF0 (the mean frequency of the basic speech tone) and sigma (the standard deviation of the frequency values comprising SF0). It was shown that the treatment of the patients presenting with mutational falsetto (MF) and functional dysphonia (FD) resulted in identical quantitative changes of SF0, namely its lowering after the treatment compared with the elevated level before it. At the same time, the measurement of sigma revealed the qualitative difference between these characteristics. Specifically, sigma decreased in the patients with MF and increased in FD. It is concluded that variability in the constituent frequencies of SF0, besides its quantitative changes, should be taken into consideration, when estimating the results of the correction of functional voice disorders.