This is Volume XII of twenty-one in a series on Cognitive Psychology. Originally published in 1930, this book is addressed to the general reader, with a preference for him or her that is interested in Speech from one or other of its practical aspects, namely, as a means for communicating and recording ideas, as the basis of the arts of literature poetry and song, or as one of the principal accomplishments distinguishing man from the lower animals. Some of the results arrived a t may be of interest to linguists, to teachers of speech to the deaf, and to those musicians or scientists who are concerned in the practice or teaching of voice production and elocution, or in the improvement or "humanising" of the tone of organ pipes and other wind instruments. Its aim is to give, in simple language, an account of some personal observations and experiments on the phenomenon of human speech, and some conclusions and suggestions as to its probable origin and future development.