WAVE ANALYSIS IN REFERENCE TO ACTION IN THE EAR. 127 



only by being in a liquid and by the tectorial membrane, but also by 

 their structure. They are soft strings or bands loaded with various cells 

 and connected with each other, or, rather, they are merely thickened fibers 

 of a membrane. It is quite impossible that they should resonate Uke 

 brass globes; they are rather to be compared to the water resonators 

 described above (p. 113). We have, therefore, to reckon with the highly 

 significant fact that the ear resonators respond to a range of tone whose 

 extent depends on the amount of damping. A single vibration arriving 

 in the ear will arouse a whole group of fibers. Another vibration of a 

 different pitch will arouse a different group. Hehnholtz himself recognized 

 this fact,* but did not see that here again not even the remotest analogy 

 could be drawn between the process in the ear and the simple harmonic 

 analysis. 



How are the sensations of tone to be accounted for on the basis of 

 the vibration of the fibers in groups? 



Concerning the physiological process in the ear the following may 

 be accepted as facts. Owing to the friction in the ear, each vibration — 

 even a simple sinusoid — arouses a set of fibers. Each fiber has its special 

 nerve which sends a stimulus to the brain whenever it is aroused. Just 

 how this is done and what kind of nerve current passes are matters con- 

 cerning which nothing need be said. What happens further in the brain 

 is absolutely unknown. 



The following psychophysical facts are recognized. A periodic series 

 of impulses reaching the ear is heard as a single tone with a specific musical 

 timbre. For example, the vibrations from a fork of 100 per second are 

 heard as a tone of a certain pitch with the smooth "fork-timbre," or "u- 

 timbre." The puffs from a siren of the same number per second are heard 

 as a tone of the same pitch, but with different timbre, depending on the 

 form of the puffs. The vibrations of a labial pipe, of the various musical 

 instruments with the same frequency, etc., are heard as tones of the same 

 pitch, but with different timbres. Physically the tones of the musical 

 instruments may be analyzed into series of partials and the puffs may be 

 likewise represented, but mentally there is at the outset no such analysis. 

 It is a fundamental principle of mental fife that groups of stimuU, even 

 for several sense organs at once, may appear mentally as single impres- 

 sions; these single impressions may be experimentally analyzed into simpler 

 groups, but the mind does not perform such an analysis without help. 

 The timbre of a tone is not analyzed directly by the mind. 



From those two sets of facts we are forced to conclude that a group 

 of nerve impulses aroused by the set of fibers produces mentally the 



♦Helmholtz, as before, 243. 



