Human Judgement

In this experiment, learners A and B showed many pronunciation errors in several phonemes. In general, it is well known that the non-native learners from Korea, China, Taiwan, have pronunciation problem on voiced-voiceless distinction: e.g., /d/ /t/, /g/ /k/, etc. The following tendencies were observed by human judges.

(1)

Learner H tends to pronounce /u/ instead of /o/.

(2)

Learners A and B were turned out to make an error between voiced and unvoiced sound. In this case, they mispronounced /t/ for /d/.

(3)

Learner B did the same error as the above. More specifically, he did /t/ for /d/ sound; e.g., [kyoodo] not [kyooto], [wadashi] not [watashi].

(4)

Learner A and B frequently mispronounced /sh/ for /s/ sound; e.g., [mosimosi] not [moshimoshi], [watasi] not [watashi]. It is generally known that for /sh/ sound, non-native speakers tend to pronounce /s/ sound[26].

(5)

Learner B made an error between /z/ and /j/.

The use of relative thresholds correlated well with human judgement, along with effectively detecting pronunciation errors. For some phonemes such as /m/, /n/, /r/, rather, the native model speaker showed score degradations. In a sense, the use of multiple native speakers is thought to be more reasonable as a criterion of threshold function.