Speech is uniquely human. Humans have both a “prewired” brain capable of learning and conveying abstract ideas, and the physical anatomy (mouth, throat, tongue, larynx, etc.) to produce a wide range of sounds. Only a few animals can approximate some human sounds.
Because the human larynx is low in the neck, a long air column lies above the vocal cords. This is important for making vowel sounds. Becuse apes lack this long air column, they cannot make clear vowel sounds. The back of the human tongue, extending deep into the neck, modulates the air flow to help produce consonant sounds. Apes have flat, horizontal tongues, incapable of making consonant sounds.
Even if an ape could evolve all the physical equipment for speech, that equipment would be useless without a “prewired” brain for learning language skills, especially grammar and vocabulary.
Walt Brown, Ph.D., “In the Beginning: Compelling Evidence for Creation and the Flood,” Center for Scientific Creation 2001, p.8