354 Prof. S. P. Thompson on the Phenomena 



except through the tubes. Under these circumstances very 

 distinct beats were heard ; and they were beats exclusively of 

 the lower note. Here, however, a very curious subjective 

 phenomenon presented itself, similar to that noted in the 

 author's earlier researches in the case of unisons in different 

 phase: the beats of the lower notes did not seem to be mere 

 maxima and minima of loudness; they were heard as a moving 

 of the lower tone backward and forward from the ear to the 

 back of the head. 



(c) Mistuned Twelfth. — For this interval the arrangement 

 with stopped organ-pipes was reverted to, the higher note 

 being raised and lowered in pitch. To one ear the higher 

 note simply rose and fell in pitch without the least throb. To 

 the other ear the lower note merely throbbed. Extreme mis- 

 tuning, so that the beats became too rapid for distinction (at 

 60 or 70 per second), yielded no differential tone, though such 

 was heard strongly when the two sounds were mingled together 

 before reaching the ears. 



An experiment with tuning-forks gave a similar result. 



At this stage resonators, consisting of rectangular boxes 

 closed at one end, were tried, with the result of bringing out 

 the phenomenon much more loudly. The beats of the lower 

 note are not subjective. 



(d) Mistuned Double-octave. — The mistuned double-octave 

 gave equally marked results. When the upper note was 

 altered the effects in the ears were as follows : the lower note 

 throbbed; the upper note merely rose and fell in pitch. When 

 the lower note was altered the upper remained unchanged, but 

 the lower rose and fell and throbbed. 



Experiments on Interference between Objective and Subjective 



Tones. 



4. The author has tried to produce interference between an 

 objective and a subjective tone in the following manner : — 

 In the spring of the present year, after a violent catarrh he 

 was troubled at intervals for several days with a " singing " in 

 the left ear of a shrill note somewhere near d" f . He tried 

 several times to produce a note within beating-distance of this; 

 but not having forks for this octave, nor of a lower octave 

 sufficiently near, he did not succeed in the attempt before the 

 ailment vanished. 



He has, however, succeeded in another case. After listen- 

 ing for a considerable time to a note that is played very loudly, 

 the ear becomes fatigued and hears the note less loudly ; but 

 when the note ceases to be played, it is still heard ringing in 



