208 M. Savart on the Mechanism of the Human Voice. 



ly used for modifying, sometimes suddenly, and sometimes 

 gradually, the number of vibrations of the air. When they 

 are stretched, their height diminishes, and, consequently, the 

 sounds become more acute, at first, because the sides which 

 contain the column of air are then more resisting, and after- 

 wards because the extensible part of these sides has a less 

 extent. At the same time that the effect is produced, the 

 orifice by which the air escapes from the trachea becomes 

 narrower, and the external side of the ventricles assume also a 

 greater degree of rigidity, for it is the same muscle which 

 produces all these movements. When these folds are un- 

 stretched, the contrary phenomena take place, and the sounds 

 become more grave. 



From the explanation we have now given of the mechanism 

 of the voice, it is evident that, if we remove the upper parts 

 of the vocal tube, and reduce it to the ventricles alone, we shall 

 not diminish the number of sounds which the voice may yield >• 

 the gravest will only become feeble. This explains why we 

 may make similar incisions in living animals without their 

 ceasing to emit different sounds. The air contained in the 

 ventricles may sound independently of that which is in the vo- 

 cal tube ; and, it is to be presumed, even if that tube under- 

 goes no alteration, that certain sounds may be produced from 

 the ventricles alone, particularly those which are occasioned by 

 grief, and, perhaps, also those which are heard when we sing 

 above our voice. This ought to happen every time that the 

 extensible part of the vocal organ cannot take the degree of 

 tension necessary to produce the required sound. This as- 

 sertion is the more probable, that there are animals, such as 

 frogs, in which the vocal organ is reduced to the ventricles 

 alone. The larynx of these animals resembles a small kettle- 

 drum. Its convex side is cartilaginous. It is situated inferi- 

 orly, and traversed by an elongated orifice which can open at 

 pleasure : The lower side is membranous, and has an orifice 

 corresponding to that of the convex side. The air having 

 arrived below this membrane, traverses the two orifices, and 

 sets in vibration the air contained in the cavity. The me- 

 chanism is the same as in Fig. 1, and as in the human ven- 

 tricle. This apparatus, simple as it is, would yet be capable 



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