Automatic Evaluation of Tracheoesophageal Telephone Speech

The tracheoesophageal (TE) substitute voice is currently state–of–the–art treatment to restore the ability to speak after laryngectomy. The intelligibility while talking over a telephone is an important clinical factor, as it is a crucial part of the patients’ social life. An objective way to rate the intelligibility of substitute voices when talking over a telephone is desirable to improve the post–laryngectomy speech therapy. An automatic speech recognition (ASR) system was applied to 41 high quality recordings of post–laryngectomy patients. The ASR system was trained with normal, non–pathologic speech. It yielded a word accuracy (WA) of 36.9%±18.0%; compared to the intelligibility rating of a group of human experts the ASR system had a correlation coefficient of -.88. After downsampling the 41 recordings to telephone quality, the ASR system reached a WA of 26.4%±13.9% leading to a correlation coefficient of -.80. These results confirm that an ASR system can be used for objective intelligibility rating over the telephone. Samodejna evalvacija traheoezofagalnega telefonskega govora Traheoezofagalni nadomestni glas je trenutno najsodobnejši način obnove sposobnosti govora po laringektomiji. Razumljivost pri telefonskem pogovoru je pomemben kliničen dejavnik, saj predstavlja ključen del pacientove socialne interakcije. Za izboljšanje govorne terapije po laringektomiji je zaželen objektiven način ocenjevanja razumljivosti nadomestnih glasov pri telefonskem pogovoru. S sistemom za samodejno razpoznavanje govora (SRG) je bilo pregledanih 41 visoko kakovostnih posnetkov pacientov po laringektomiji. Sistem SRG so učili z normalnim, nepatološkim govorom. Odstotek pravilno razpoznanih besed je bil 36,9%±18,0%; v primerjavi z ocenami razumljivosti, ki jih je podala skupina strokovnjakov, je imel sistem SRG korelacijski koeficient -,88. Po znižanju frekvence vzorčenja 41 posnetkov na telefonsko kakovost je sistem SRG dosegel naslednji odstotek pravilno razpoznanih besed: 26,4%±13,9% oziroma korelacijski koeficient -,80. Ti rezultati potrjujejo, da je sistem SRG primeren za objektivno ocenjevanje razumljivosti telefonskega govora.