This paper explores the acoustic characteristics of the human speech signal (used for communication purposes), proposing that they can derive from an adaptive evolution of the cetaceans’ echolocation signals. Nevertheless, the modern human speech signal is far more complex than that of animal echolocation. Indeed, this evolution began before Homo sapiens, probably at the time of the H. erectus. The comparison between the whale and Homo sapiens can allow us to describe the acoustic features of human speech as the result of a co-evolution of the system of acoustic localization of objects in the common space inherited from mammals and specialized only by humans in order to allow them more sophisticated uses of their sensory apparatus. Although it is impossible to adduce material proofs, there is inferential evidence arising from comparing archaeological, paleontological, biological, acoustic, and linguistic data.