58 



THE STUDY OF SPEECH CURVES. 



VwVv./V-VI^-'^'L' 



apparently the axis of several waves. The horizontal axis of the already 

 adjusted ocular (upper lens focused on the cross lines) is then made 

 to coincide with the axis seen through the microscope. When the micro- 

 scope is moving horizontally the horizontal line of the ocular will remain in 

 the axis if all adjustments are correct. A difficulty lies in the fact that the 

 ocular scale has to be read over the dark surface of the smoked paper. 

 An ordinarv^ scale is hardly visible. Various means of producing a white 

 scale and illuminating it in the ocular have been tried, but without success. 

 A scale with thoroughly blackened lines (as in the Leitz ocular) works suc- 

 cessfully when the plate is well illuminated. Each time before use the upper 



lens of the ocular is 

 A-i - ^ —a focused on its scale; 



Z\ I t^z\ ( the microscope is then 



focused on a millimeter 

 scale. The relation be- 

 tween the scale of the 

 ocular and the millime- 

 ter scale is then read 

 off; for example, 50 

 divisions in the ocular 

 =^10mm. If the two 

 scales do not corres- 

 pond in some simple re- 

 lation — for example, if 

 50 divisions =^ 10.3mm. 

 — the ocular is slightly 

 drawn out or pushed in 

 and the whole micro- 

 scope then refocused. This is repeated till some simple relation (1:10, 

 1 : 5, etc.) is obtained. 



The simplest problems involving quantitative analysis are found in 

 the studies of duration, amplitude and melody; the methods will now be 

 described. 



For a study of the duration of sounds a long millimeter scale is used. 

 It is laid horizontally along the speech curve; the reading for the beginning 

 of the sound is taken, then the reading for the end; the latter at the same 

 time is the reading for the beginning of the next sound (or pause), etc. 

 The scale should not be unnecessarily moved. The difficulty arises in 

 assigning the limits between speech elements. This is due in the first place 

 to the fact that speech elements have no absolutely definite limits. One 

 sound shades off more or less gradually into the next one; even the passage 



Fig. 45. — Coordinate measurer. 



