THE EAR AND HEARING. 
283 
sentiments awakened by musical tones are due to myriads of 
associations with the voice, vocal cries having been the 
commonest mode of expressing emotion through the various 
stages of animal development; whilst Darwin referred this 
phenomenon more especially to associations of vocal sound 
and deep sexual emotion built up during the courtships of 
unnumbered species; but we must leave this interesting 
subject for treatment by others. 
Irregular vibrations produce simply noises, the perception 
of which some consider to be mainly due to the irregular 
irritation of the nerves by the otoliths. Although in music 
less intervals than a semitone are not admitted, the ear can 
distinguish still smaller differences. A quarter tone makes a 
marked difference to an ordinary ear, whilst a good musician 
can distinguish two tones whose vibrations are as 1,149 to 
1,145, sounded after each other, and even a smaller difference 
if they are sounded together. Two pitchforks, whose number 
of vibrations per second are 1,209 and 1,210, sounded simul¬ 
taneously can be distinguished by a first-rate ear. 
The concurrence of two or more sounds may be pleasing 
or displeasing, irrespective of their individual character. The 
pleasurable concurrence is called harmony. It is dependent 
upon the numerical vibrations of the two sounds. Simple 
ratios as 1 to 2 (octave), 2 to 8 (fifth), 3 to-4 (fourth), 4 to 5 
(major third), 5 to 6 (minor third), are harmonious in the 
order stated. All these are admissible in musical compo¬ 
sition, and are termed chords. The combination 8 to 9 (a 
single tone) is a dissonant combination ; 15 to 16 (a semi¬ 
tone! is a yratiny discord. In the lowest audible notes, as in 
a very deep crgan note, the auditory sensation tends to lose 
itself in the tactual and organic sensations due to the vibration 
of the air, floor, &c. The duration of an impression of sound 
would appear, from the experiments of Savart, to be less than 
one-tentli of a second, since a series of beats begins to be felt 
as continuous when it numbers ten to twelve per second. 
III.— Quality, timbre, or Jdany, is explained by Helmholtz 
by the presence of auxiliary upper tones, e.y., it is found that a 
note sung by the human voice, or struck on a violin, is much 
fuller and finer in quality than one uttered by a flute, and 
this difference exactly corresponds to the variation in the 
number of the upper tones present. When the note is nearly 
destitute of upper tones, as in the case of a stopped organ 
pipe, it is thin and poor, and does not minister to the proper 
enjoyment of klang. lie also states that the difference in the 
vowel sounds is due to the nature of the upper tones associated 
with the ground tones, e.y .— 
