ABSTRACTS OF 'TECHNICAL ARTICLES 173 



enhances the effect. With an extreme preHminary anneal of 1400° C. 

 for 18 hours specimens of 65 permalloy have been obtained with the 

 record value of maximum permeability of 600,000. The magnetic 

 characteristics of materials treated in this way are relatively insensitive 

 to stress. These magnetic characteristics are, however, highly aniso- 

 tropic; the maximum permeability in one direction is as much as 150 

 times as large as that at right angles. 



Newer Concepts of the Pitch, the Loudness and the Timbre of Musical 

 Tones} Harvey Fletcher. It has generally been thought that 

 corresponding to the three psychological aspects of a sound, namely, 

 the pitch, the loudness and the timbre, there are the three physical 

 aspects of a sound wave, namely, the wave-length, the amplitude and 

 the wave form. Although it is true that there is such a correspondence 

 in a very approximate way, when the matter is examined more closely 

 it is found that each of the psychological aspects depends upon all 

 three of the physical properties of the sound wave. 



In the paper it was shown how loudness can be defined in a quantita- 

 tive way and measured by experimental methods which are described. 

 From such measurements a relation has been found between loudness 

 as it is ordinarily understood by the lay man and the physical intensity. 

 In the higher intensity regions it is found that if the intensity of a 

 sound is increased 1000-fold then the loudness will be increased 10-fold. 

 In other words in these regions the loudness as determined by the 

 average observer is proportional to the cube root of the intensity. For 

 the lower intensities the loudness increases more rapidly than for the 

 high intensities, being almost proportional to the intensity in the 

 regions near the threshold. It is shown that the loudness depends 

 upon the frequency, the overtone structure and the intensity of the 

 complex sound. 



In a similar way a precise definition of pitch is given which makes it 

 possible to make quantitative measurements of this psychological 

 aspect of a sound. Contrary to the usual notion it is found that the 

 pitch varies not only with the fundamental frequency but also with 

 intensity of the sound and with the overtone structure. For example, 

 it was found that the pitch of a tone having a frequency between 100 

 and 200 cycles may be lowered more than a full tone by increasing the 

 intensity without changing the frequency. Also it was shown that the 

 pitch of a complex tone may shift as much as 1 or 2 octaves by changing 

 the overtone structure. Numerous examples are given to show that 

 pitch also depends upon the three physical quantities, frequency, over- 

 tone structure, and intensity. Although quantitative measurements 



^ Jour. Franklin Institute, October, 1935. 



