The Hydraulic Principles Governing the Function of the Cochlea

General equation. Rejecting all fantastic “anatomical” data, that is, not making any anatomical assumptions but those of facts which are clearly visible under the microscope, but, on the other hand, taking conscientiously into account everything that can thus be seen, we derive a general equation describing the hydraulic functions of the mammalian cochlea.

Statement of the chief aim of the theory. Whenever anything occurs on the outside which deserves to be called a sound in the sense of the physicist, and which varies more or less periodically with the time, we want to know first, what length or lengths of the phragma will be involved, because this determines the number of sensitive cells stimulated and thereby the magnitude of the nervous flux (or “the sensation intensity,” loudness); and we want to know second, how frequently per time unit these various lengths of the phragma are shaken, because this determines the nature of the stimulation and accordingly the quality of the chemical process resulting in each of those sensitive cells (or “the sensation quality,” pitch). Thus, our most important aim must be the establishment of a relation between l and t.

Solution of the equation. The equation is solved in special cases for two-fold verificaton: (1) by auditory observation; (2) by experimentation on a large, transparent, hydraulic model.

Thirty years without adverse criticism. The hydraulic theory during its life of thirty years has received some praise by the few who were willing to read it, has been viciously misrepresented by some who would not or could not comprehend it, has been innumerable times dogmatically rejected by those who did not even know what it consists in. We invite serious criticism of its basic assumptions, its mathematical analysis and, last but not least, its agreement with the facts of hearing.

The concept of a “traveling” bulge is not a part of the hydraulic theory. The author requests textbook and magazine writers to cease misquoting him. He has never either enounced or supported any “traveling” bulge theory.