One study showed that 35-41% of English proficiency judgments in classroom presentations were explained by prosody quality,[2] notably including the accuracy of word stress placement and the use of a wide pitch range.
In a seminal study[4] Gumperz observed a group of cafeteria workers from South Asia who had been called out, by their British customers, for being disrespectful.
Gumperz noticed that the way they offered side dishes, with a falling intonation, gravy>, conveyed, to the English speakers, a message of “take it or leave it, I don’t care”.
This illustrates how misperceptions of prosody, with its powerful interpersonal functions, can cause mere language differences to be attributed to bad attitudes and improper intents, especially in cross-cultural situations.
Even adept speakers may feel inadequate in high-stakes situations, such as public speaking, and may turn to coaching to project more charisma.