RECENT PSYCHOLOGICAL RESEARCH 
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points in localization we call loops. Midway of these are other 
median localizations known as nodes. There is a fundamental 
difference between these nodes and loops. In the loop the phan- 
tom sound moves in the same direction in which the observer is 
moving, while in the node it moves in the opposite direction. 
Following are some of the conclusions which we have reached : 
1. If a rich tone is used the trained observer may localize, 
not only the phantom for the fundamental tone, but at least two 
or more of the overtones the phantoms of which have loops of 
relatively smaller dimensions may be localized independently of the 
overtone. This is particularly true of low tones of some 100 v.d. 
2. The loops and nodes of any phantom always occur alter- 
nately for each one- fourth wave length of the phantom tone in 
the case of either a pure tone or a rich tone, and may be inter- 
preted in terms of the conditions of the standing wave. 
3. Wave phase effects obtain, not only in the line of the re- 
ceivers, but practically anywhere within the range of audibility. 
We are as yet unable to say that these changes in phase are 
everywhere uniform. Present investigations seem to point to 
the fact that they are not uniform. 
4. Wave phase effects are best obtained midway of the receiv- 
ers. As we draw near either of the sources localization becomes 
more difficult. 
5. The size of the loops varies directly with the wave length of 
the sounds used. The same is true of the nodes. 
6. Wave phase effects in open air are best observed with 
tones ranging from 300 v.d. to 1200 v.d. This is because (1) 
tones within these limits present sharper differences in intensity 
at the nodes and loops; (2) the interaural distance hinders locali- 
zation with tones of high pitch. 
7. The flux in intensity from a loop to its adjacent node has 
been determined by means of the Seashore audiometer. Hence 
the differences in intensity which we had formerly observed are 
not at all subjective. 
8. The intensity of the two sources may vary widely without 
affecting the wave phase effect. 
9. By means of the standing wave it is possible to predict the 
relative intensity and localization of the phantom at any point on 
the line between the receivers. 
