Klaske van Sluis

Objective and subjective voice outcomes: a systematic review 33 the present review the results for both groups of listeners were pooled [43]. One study [40] performed perceptual evaluation of TES compared to healthy speakers on a VAS 0-100. Another study [48] used a one to seven equal-interval scale for rating. A score of one indicated severe hoarseness, while a score of seven indicated a clear voice quality. A scale of one to seven was also used in another study [54], in which evaluators rated videotaped speaking fragments of ES, TES and ELS for voice quality [54]. The level A rated study of Eadie et al. [30] found that TES are rated with a significant more acceptable voice quality compared to ELS (Table 4). When speakers had to judge their own voice recordings no differences were found in speech acceptability between TES and ELS [30]. Two other studies [46, 48] also found better voice quality outcomes for TES compared to ELS, though these differences were non-significant [46, 48]. Three studies [43, 48, 54] found a better voice quality for TES compared to ES, which was significant in one of these [54]. In one study [43], ELS was rated as having a better voice quality compared to ES and TES. Another study indicated ES as having a better voice quality compared to ELS [48]. When a comparison between substitute voice speakers and healthy speakers is made, the group of healthy speakers is rated to have the best voice quality [40, 54]. One study underlined this with significance [54]. Intelligibility In eight studies [30, 31, 36, 40, 43, 46, 48, 54] ( n =329) intelligibility was as- sessed, and two of these were level A studies [30, 31], and six level B studies [36, 40, 43, 46, 48, 54]. Different methods were used to measure intelligibility outcomes. Two studies [48, 54] used a self-developed seven-equal interval scale, while one study [40] used a VAS of 0-100. The VAS and interval scales were used to rate the speakers’ intelligibility. Two studies [30, 43] used the Sentence Intelligibility Test (SIT) to perform a per protocol analysis. Other studies de- veloped their own assessment procedure. One study [36] evaluated TES with a group including ES as well as ELS under different conditions. Outcomes are presented with the percentage of correct heard words [36]. Another study [31] performed a telephone listening task where words and sentences of TES and healthy speakers were transcribed. One more study [46] evaluated audio sam- ples on intelligibility in ES and TES by phoneme confusion matrices. In this study no overall intelligibility scores were given [46]. Comparative group outcomes are shown in Table 2.4. For the speech reha- bilitation methods TES is mostly rated to have a better intelligibility compared to ES and ELS. In two studies [30, 54]. including the level A rated study of Eadie et al. [30], this is confirmed with significance [30, 54]. In one study, ES is rated to have a significantly better intelligibility compared to ELS [54]. The intelligibility of healthy speakers is rated as superior compared to the speech rehabilitation methods. Two studies [31, 54], including the level A rated pub- lication of Crosetti et al. [31], indicated that this difference was significant. In one study [36], a comparison was made between the group of TES and a