94 ox THE PHYSIOLOGICAL CAUSES OF 



or the twelfth of the fundamental tone, has no practical 

 interest for us, and never occupies our attention. The 

 upper partials are consequently thrown into that un- 

 analysed mass of peculiarities of a tone which we call its 

 quality. Now as the existence of upper partial tones 

 depends on the wave form, we see, as I was able to 

 state previously (p. 74), that the quality of tone corre- 

 sponds to the foTTn of wave. 



The upper partial tones are most easily heard when 

 they are not in harmony with the fundamental tone, as 

 in the case of bells. The art of the bell-founder consists 

 precisely in giving bells such a form that the deeper and 

 stronger partial tones shall be in harmony with the 

 fundamental tone, as otherwise the bell would be un- 

 musical, tinkling like a kettle. But the higher partials 

 are always out of harmony, and hence bells are unfitted 

 for artistic music. 



On the other hand, it follows, from what has been said, 

 that the upper partial tones are all the more difficult to 

 hear, the more accustomed we are to the compound tones 

 of which they form a part. This is especially the case 

 with the human voice, and many skilful observers have 

 consequently failed to discover them there. 



The preceding theory was wonderfully corroborated by 

 leading to a method by which not only I myself, but 

 other persons, were enabled to hear the upper partial 

 tones of the human voice. 



No particularly fine musical ear is required for this 

 purpose, as was formerly supposed, but only proper means 

 for directing the attention of the observer. 



Let a powerful male voice sing the note e b ^: -t?y- to 



the vowel o in ore, close to a good piano. Then lightly 



touch on the piano the note V b 'W^^ in the next octave 



