448 



THE HUMAN MOTOR 



The same scientist observed a pressure of -3 metres in playing 

 a clarionet. As the gaseous exchanges are considerably increased 

 in this exercise the work expended in phonation rises to about 

 550 or 600 kilogrammetres. 



Marage ( l ), who made certain investigations in the year 1904, 

 describes two interesting cases. The first was that of a man who 

 had undergone the total ablation of his larynx. Marage by means 

 of a flexible tube effected a junction between the patient's trachea 

 and a membraneous rubber reed fixed to an artificial palate. This 

 tube was connected to a manometer which indicated a pressure 

 varying from -1 m. to -2 m. during ordinary conversation. The 

 quantity of air expired per hour was 2,07( litres. Hence : 



T = 2,070 X 2 X To = 621 kilogrammetres. 



The second subject ( 2 ) had a tracheotomy tube enabling H to 

 be measured. The average value was -13 m. and the volume of 

 air V 300 litres. Hence when at rest : 



T = 300 X 2 X -13 = 78 kilogrammetres. 



The experiment with the artificial larynx does not represent 

 natural conditions, the efforts are abnormal, and the volume of 

 air expired per hour (2,070 litres) was excessive. Such conditions 

 are fatiguing. 



With the second subject, when speaking in a large room, V was 

 1,440 litres and H varied from 10 to 20 centimetres. Hence T 

 issued from 288 to 576 kgm. An average of 434 kgm. We may 

 infer that with the natural larynx the work done in phonation 

 may vary from 50 to 600 kilogrammetres. 



The expenditure of energy is very considerably increased when 

 the speaker has to make himself clearly heard throughout a large 

 hall. The comparative effort, needed with various qualities of 

 voices, to attain equal range and distinctness, has been measured 

 by having the same note sung by three singers, a bass, a baritone, 

 and a tenor. The comparative results were as follows : 



( x ) Marage (Journal de Physique, 1908, p. 298). 



() Id., Ibid., and Physiologic de la Voix, Paris, 1911). 



