Formant analysis of stressed /i:/ and /I/, as compared to the typical values of a female British RP speaker as per Table 1
Formant plotting of stressed /ae/, /[??]:/ and /[??]/, as compared to the typical values of a female British RP speaker as per Table 1
dialects; it can be pronounced weakly with the tongue forward, behind the upper front teeth [r] as in Network Standard; it can be trilled or burred in the same position [rr] as in Scots English; it can also be slurred in this position to become the schwa [e] (the indeterminate sound of unstressed vowels), which blends with the preceding vowel, as in British RP, New England, and working class accents in the Northeastern U.S., as well as the patrician Northeastern (Franklin Roosevelt) and Southeastern (Scarlet O'Hara) accents.
One fifteen-year-old that we spoke to on Tangier Island, in giving the name of a business, used an [e] in the first name "Charles," as is common in British RP and some Northeastern and Southeastern American dialects, and a standard American R in the last name "Charnick." Crystal speculates that the latter was the common pronunciation in early modern English.