oxidant on the Vocal Fold

Objectives: Diplophonia is a common and often misinterpreted symptom of disordered voice and needs objectification. It was hypothesized that diplophonia is produced by two distinct oscillators, which yields a profound physiological interpretation. Based on that hypothesis, an audio signal processing algorithm for the detection of diplophonia is proposed, tested and validated. Its performance is compared to the clinical standard parameter Degree of Subharmonics (DSH). Study design: Prospective. Methods: 50 dysphonic (28 diplophonic and 22 dysphonic without diplophonia) and 30 euphonic subjects were included in the study. From each subject up to five sustained phonations were recorded during rigid telescopic high-speed video laryngoscopy. 185 phonations were split up into 285 segments of distinct voice qualities. In accordance to the clinical group allocation, the considered segmental voice qualities were 1) diplophonic, 2) hoarse without diplophonia and 3) euphonic. To analyse the segments, an analysis-by-synthesis procedure was proposed. The Diplophonia Diagram is a scatter plot that relates the one-oscillator synthesis quality SQ1 to the two-oscillators synthesis quality SQ2. Multinomial logistic regression was used to distinguish diplophonic from nondiplophonic segments in the Diplophonia Diagram. Results: Diplophonic segments could be well distinguished from non-diplophonic segments in the Diplophonia Diagram, because two-oscillators synthesis is more appropriate to imitate diplophonic signals than one-oscillator synthesis. Detection of diplophonia using the Diplophonia Diagram clearly outperforms the DSH by means of positive likelihood ratios (56.8 versus 3.6). Conclusions: The diagnostic accuracy of the newly proposed method for detecting diplophonia is superior to the DSH approach, which should be taken into account for future clinical and scientific work.