The pronunciation of a coming after certain initial consonants as e, is the most important of the vowel changes met with in the Indo-Aryan loanwords of Malayāḷam, and also perhaps the most interesting from a phonological point of view.
The first to note and record the change was Gundert. He observed that a occurring after the voiced sounds g, j, d, d, y, and r is heard as e in the pronunciation of the Malayāḷis (A Grammar of the Malayalam Language, 2nd ed., p. 8). Gundert's observation is obviously imperfect inasmuch as the change is regularly manifested after b and l also, over and above the sounds specified by him.