Introduced in Volo's Guide to Monsters, Kenku can only speak by imitating sounds they've heard — they're unable to speak with their own voices (p. 110):
Although unable to speak in their own voices, kenku can perfectly mimic any sound they hear [...] [K]enku cannot create new sounds and can communicate only by using sounds they have heard.
What does it sound like when talking with a kenku?
Does the quote above mean that each mimicked piece of speech they use sound exactly as they heard it, including the original speaker's voice? Do they only use entire whole phrases they've heard, or do they piece together sentences from different sounds they've heard in different phrases? If the latter, is each word going to be using a different voice?