Dogs and cats in the house、horses and sheep in the barn、whales and dolphins in the ocean、even insects in the forest、all of these creatures can make distinct sounds (including some ultrasounds which cannot be heard by human)、and some of them can imitate human voice and even give a great interaction、watch the clip below and give this smart fowl fellow a big hand!

Einstein

So、how about we humans? Are we competent enough to bit the bird?
Let's see the limitation of human voice:
Georgia Brown-Brazilian singer (see whistle register)
Basso profundo-the lowest note
Dean Frenkel (harmonical singer)

So far、we are only aware of the pitches that human beings can make、in the next section、we are going to think about the connections between auditory and speech mechanisms、and see how brain works when we are talking. And in section 2 we will try to discover how the vocal tract works to produce speaking voices. In the last section、we are going to focus on the accent of speech、and discuss the cause.