Importance of prosody in English
Is there any good research on the importance of prosody for intelligibility (in English)? Not just books /web sites claiming this and that, but hardcore research? I have heard a claim that actual phonetics accounts only for 25% of all intelligibility and, frankly speaking, I don't buy this claim. Prosody is clearly important, but did any one try to quantify this? It is also very interesting if somebody tried to pinpoint specific prosody aspects. For instance, many non-native speakers put stress correctly (most of the time), but intonations and rhythm can be harder to get. How much does this affect understanding?
Thanks a lot in advance!