As for your hearing a voice that spoke, coming not from the eagle’s heads but from the midst of his body, this is the interpretation: This verse refers to 2 Esd 11.10. The footnote in Revised Standard Version concerns a purely translational matter, so it is not needed. Revised Standard Version changes the Latin pronoun for “his” to the eagle’s for clarity. Revised Standard Version and Good News Bible differ in the place where verse 18 begins. We recommend following Good News Bible for verse 17, in wording as well as verse numbering. Contemporary English Version is also helpful, saying:

• You heard a voice coming from the eagle’s body instead of from any of its heads.

Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on 1-2 Esdras. (UBS Helps for Translators). Miami: UBS, 2019. For this and other handbooks for translators see here.