More problematic deviations may arise when the difficulty in perceiving and realizing phonetic features of the target language that are not distinctive in the mother tongue leads non-native speakers to blur the distinction between phonemes in the target language, thus producing one phoneme instead of two distinct ones.
As splitting criteria, we used the bMCU mean, the bMCU median, the age median, gender, mother tongue (native speaker and non-native speaker), specialization (science and non-science), and prior instruction (yes and no).
Furthermore, experiments on speech reception in background noise reported that native listeners (i.e., subjects that listen to speech sounds of their mother tongue) have an advantage over non-native listeners in identifying keywords in sentences masked by background noise [11].
Finally, Elisabeth Pain, our contributing editor for South and Western Europe, writes that the challenges of publishing for non-native English speakers go well beyond struggles with a foreign tongue.
To some people's likely immediate 'but what if they become invasive?' reaction to the idea of introducing non-native species to islands, I would like to respond with two final tongue-in-cheek remarks.
Non-native speakers are likely to replace target language phonemes by phonemes from their mother tongue [3, 5].
For example, while some countries such as Australia and Spain have many immigrants with the countries' official language as their mother tongue, in most countries (e.g., Germany or Sweden) immigrants are non-native speakers of the countries' official language(s).
When the non-native speech is heterogeneous in the sense that it is produced by speakers with different mother tongues, as in our case, it may be extremely difficult to capture the rather diffuse pattern of variation by including variants in the lexicon (see also [4]).
