Is it permissible in the Adhan to prolong the word "Akbar"?

It is not permissible to prolong the letter "Baa" in "Allahu Akbar." Whoever does so in the Athan, their Athan is invalid. Prolonging the "Baa" and its hamza, or the hamza of "Ashhadu," or the alif of "Allah" are among the mistakes that invalidate the Athan. In fact, intentionally prolonging some of these can lead to disbelief. Prolonging "Akbar" adds an alif to it, making it "akbaar," which becomes the plural of "kabar," meaning a drum.