This is a field within
psycholinguistics, of Second Language Acquisition (SLA). There's a lot on
the subject, and we'll try to keep it light as an introduction here.
There's a few reasons for why
English as a Foreign Language (EFL) students find listening difficult. It
could be a decoding problem, unfamiliar grammar, unfamiliar vocabulary, and
even unfamiliar pronunciation of particular words. Grammar can be
pre-taught, so too the vocabulary (and its pronunciation), but decoding?
Essentially, we native speakers
can decode long streams of speech with quite few problems. If I asked you
(speaking at normal speed), "What's the first thing you think about when I
ask you about 'phonology'?", you don't actually hear every syllable, but you
get every word, just the same. It is assumed that pronunciation (phonology)
and listening go hand in hand. That is, if you know how to pronounce it,
then you can hear it. So, in real life I say to you "wha'sth'firs'thin'gyu'thin'bout'wheniyask'ya'bout
phonology?" It's difficult to read, but easy to hear. For our students, it's
damn near impossible to hear (discern the words), but easy to read.
Interestingly, if it were a Korean saying this to a Japanese person, then
the Japanese person will find it much easier to understand than when it
comes from a native speaker of English. Why's that?
Well, something like the
principle of 'economy of effort' (or lack of it) (Roach 2006). We native
speakers have ways to say things quickly, smoothly, and easily (with less
effort for our mouth and muscles). This is compared to non-native speakers
like Koreans, who typically speak in a kind of EFL-ese (Rinvolucri 1999), where
they annunciate each word in clear dictionary form.
So, what's the difference?
Assimilation: Words are
blended, where the last syllable (usually consonant) is affected by the
first sound of the next word. For instance, EFL students say, "ten cars",
but native speakers say "tengcars"; "that boy", becomes "thapboy"; and "this
shirt" becomes "thishirt". (Grimson 1994)
Adding sounds: Between
vowels, we add either a /w/, /r/, or a /j/ sound, though the /j/ sound in
English is a 'y' (note in other European languages j, like 'jump', is
pronounced as 'yump' in English). So, "...to open the envelope..." would be
pronounced as "towopen the-yenvelope".
There's more, but this
is just the start.
References
Grimson, A (1994) Grimson's
Pronunciation of English (5th Ed.). London: Edward Arnold.
Roach P (2006). Phonetics,
Oxford Introductions to Language Study. Oxford University Press.
Rinvolucri, M. (1999) The UK,
EFLese sub-culture and dialect. Folio 5(2): 12-14