[Voice signal analysis in laryngeal hyperreactivity]

Increased reactions of the laryngeal mucosal membrane can appear after acetylcholine (ACH) inhalation. A red mucous membrane, vocal cord edema, mucus formation, changes in the glottic configuration and (rarely) subglottic edema are visible to laryngoscopic observations. The influence on various voice parameters in patients with and without laryngeal hyperreactivity was researched in order to decide the reliability of voice parameter measurements in clinical practice. Significant variations of the soft phonation index (SPI), the fundamental frequency variation (vFo), the noise-to-harmonic ratio (NHR) and the voice turbulence index (VTI) were examined for their correlations with the observable features of laryngeal hyperreactivity. A single diagnosis of hyperreactivity with voice parameter analysis failed in 50% of the patients examined because of functional voice instability and irregularities seen. Only with both laryngoscopy for reliable discrimination and voice parameter analysis for quantitative registration were findings sufficient for assessing laryngeal hyperreactivity.