Is there any incidence of Aakashvaani in scriptures except Krishna birth? Bhavishyavani of something in scriptures?
In fact there are lots of incidents. One example occurs in Mahabharata Vana Parva in the story of Bhageeratha. The sloka is athāntarikṣācchuśrāva vācaṃ gambhīraniḥsvanām । meaning a loud voice spoke from Aakash or Antariksha. You can refer that at https://archive.org/details/mahabharata02ramauoft page 346 (of the document, not the book) sloka 21.