Theory of Audition subjected to Experiments. 165 



sand so unfortunately base upon their mistaken view a 

 •criticism which falls wide of its mark. 



The term " resonance " used in the present connexion is 

 open to misunderstanding. In the minds of some, it recalls 

 simply the familiar case of the actual resounding for several 

 seconds by a lamp-shade of a musical sound originally due 

 to the voice or piano. Taken in this crude sense of the actual 

 reproduction of a sound probably no one, competent to 

 judge, has ever believed in a resonance theory of hearing. 

 But the essential facts of the hypothesis are present in the 

 case just referred to. The lamp-shade has a certain period 

 of vibration natural to it. But when practically the same 

 note is sung, the very feeble vibrations of the air reaching it, 

 being of the right period and repeated hundreds of times, 

 elicit a powerful response. 



If the periods had been utterly different instead of nearly 

 alike, the response would have been unnoticeable instead of 

 arresting. 



Hence the sufficiently powerful vibrational response of an 

 elastic system to very weak fore j s, owing to the almost exact 

 tuning between the period of the forces and that of the 

 responder, is of the essence of the theory of sympathetic 

 resonance, whether that responder makes any sound or not. 

 Perhaps sympathetic response would have described more 

 precisely what is intended by the commoner phrase sympa- 

 thetic resonance. 



Further, it must be borne in mind that the degree of falling 

 off in response amoung resonators, owing to their mistiming 

 with the forces impressed upon them, depends upon the 

 damping of their own natural vibrations. Thus, theory shows 

 that the more highly the vibrations natural to a responder are 

 damped, the less is the falling off of their response owing to 

 a mistiming of the impressed forces. In other words, the 

 response is more widely spread among a graduated set of 

 responders when they are highly damped, but is more con- 

 centrated when the responders are but slightly damped. 

 This may be clearly seen by reference to the plates of previous 

 papers*. 



Hypotheses of audition may be approached in a variety of 

 ways. Perhaps the most natural basis is that of dissection 

 and microscopic examination of the anatomical structure of 

 the ear. These investigations have been carried out by a 

 number of workers, among whom it may suffice to mention 



* See figa. 1. 2, & 3, Plate VIII. Forced Vibrations, &c, Phil. Mag. 

 August 1918. Plate V. Mechanical " Resonators/' &c, Phil. Mag. 

 April 1919. 



