Influence of Reading Errors on the Text-Based Automatic Evaluation of Pathologic Voices

In speech therapy and rehabilitation, a patient's voice has to be evaluated by the therapist. Established methods for objective, automatic evaluation analyze only recordings of sustained vowels. However, an isolated vowel does not reflect a real communication situation. In this paper, a speech recognition system and a prosody module are used to analyze a text that was read out by the patients. The correlation between the perceptive evaluation of speech intelligibility by five medical experts and measures like word accuracy (WA), word recognition rate (WR), and prosodic features was examined. The focus was on the influence of reading errors on this correlation. The test speakers were 85 persons suffering from cancer in the larynx. 65 of them had undergone partial laryngectomy, i.e. partial removal of the larynx. The correlation between the human intelligibility ratings on a five-point scale and the machine was r= ---0.61 for WA, r≈ 0.55 for WR, and r≈ 0.60 for prosodic features based on word duration and energy. The reading errors did not have a significant influence on the results. Hence, no special preprocessing of the audio files is necessary.