Though I think most of VanillaSwirls comments are generally confused, there are some biases that show up in this space.
In particular, people rate the intelligibility/clarity of Caucasian speakers higher than that of East Asians
even when the audio is the same.[0]
[0]: http://www.academia.edu/6126025/Expectations_on_Speech_Evalu...
Key quote from page 444:
In a typical study in this paradigm, participants listened to 4 minutes of a tape-recorded lecture produced by a native speaker of standard American English. Some participants were lad[sic] to believe that they were listening to a North American NS[native speaker] instructor, whereas others were lead to believe that the instructor was an international NNS[non-native speaker].
[...]
[I]ndeed, listeners who were exposed to the Chinese/NNS guise perceived more of a foreign accent and scored lower on a recall test than those who were exposed to the Caucasian/NS guise even though the audiotape they heard was exactly identical (standard American English).