Intelligibility of pseudo-whispered speech after total laryngectomy

This study aimed to assess the intelligibility of so-called 'pseudo-whispered speech' (pseudo-WS), as produced without voice nor pulmonic airstream by some alaryngeal patients prior to rehabilitation. Several perception tests were submitted to three experienced clinicians and three naive listeners, relying on the speech samples of 20 French native speakers: 10 alaryngeal speakers, solely using pseudo-WS when starting speech therapy up to six months after total laryngectomy, and 10 control speakers, recorded in the closest speech mode available, whispered speech (WS). Experts were asked to identify consonants (C) in the /a/+C+/a/ context and to rate intelligibility, unintended additive noise, and fluency on a likert-scale, while naive listeners completed a quantitative test of intelligibility. Intelligibility of WS was found to be high, with scores ranging from 46.33/54 to 53.67/54 (median 52.5, interquartile range 2.33) for the quantitative test, and segmental intelligibility ranging from 68.75% to 94.79% (median 87.5, interquartile range 17.71). Segmental confusion affected voicing in favour of unvoiced consonants, as previously reported in the literature. By contrast, intelligibility of pseudo-WS was found to be poor, with scores ranging from 1/54 (unintelligibility) to 28.33/54 (median 8.66, interquartile range 14.67) for the quantitative test, and segmental intelligibility ranging from 3.13% to 28.13% (median 9.24, interquartile range 14.58). Segmental intelligibility was not uniformly affected: stops, labials and unvoiced consonants were better identified than other categories. Finally, a significant correlation was found between global intelligibility and articulatory precision, while unintended additive noise and fluency seemed to play no role.