SPEECH 



'7'5 



Oral Movements in Speed) 



Articulation consists of highly complex movements 

 of the tongue, palate and lips, which constantly vary 

 the size and shape of the nasopharyngeal resonating 

 cavities. Although this has the effect of continually 

 modifying the resulting sounds, it must be borne in 

 mind that it is the movements of articulation alone 

 that give meaning — as opposed to emotional quality — 

 to speech. In suitably trained subjects, this meaning 

 may be appreciated by eye almost as readily as by 

 ear (lip reading). Indeed the actual sounds of speech 

 have been dismissed by Paget (93, 94) as no more than 

 the 'convenient consequences' of articulator^' postures 

 which are to be regarded as the primary vehicles 

 of meaning. 



The alterations in shape of the air passages above 

 the vocal cords have been studied by a combination 

 of sound films, oscillographic records of the wave 

 forms of speech (sound spectrograph}-), and radio- 

 graphic examination of the head (6j, 67, 100, no, 

 111). Thus it has been shown that not all speech 

 sounds entail characteristic lip positions and that 

 there is in general less rigidity in 'vocal posture' 

 than is commonly supposed. For instance, the posi- 

 tions of the tongue formerly deemed essential to the 

 pronounciation of particular speech sounds in fact 

 show considerable variability. Application of these 

 methods to the stud) of \arious speech disorders may 

 be expected to produce valuable results. 



Esophageal Speech 



An artificial larynx, of the type devised by the 

 Bell Telephone Laboratories [Fletcher (37)], was at 

 one time widely advocated for use in cases with 

 complete excision of the larynx and the establishment 

 of a permanent trachectomv . This procedure is open 

 to objection (118, 121), however, and in recent years 

 has been supplanted increasingly by the technique of 

 esophageal speech. In such cases, air expelled from 

 the esophagus may cause the production of sound 

 ('pseudo-voice' ) through vibration of the contracted 

 edges of the esophagus itself. The mechanism has been 

 carefully studied by Bateman and associates (6, 7) 

 who report measurements of esophageal pressure and 

 chest movements in 3 cases in which the esophageal 

 movements were observed by fluoroscopy. Their 

 observations support the view of Negus (90) that the 

 cricopharyngeal sphincter plays an essential role in 

 the recovery of speech. This sphincter is released when 

 the patient is about to speak, allowing the esophagus 



to fill. This occurs rapidly in view of the negative 

 intrathoracic pressure to which the esophagus is 

 exposed, reinforced by a firm inspiratory effort. The 

 patient then closes the sphincter and causes the 

 intrathoracic pressure to rise by means of a strong 

 expiratory effort. The resultant rise in esophageal 

 pressure forces some air through the sphincter, pro- 

 ducing a sound which is modulated by lip and 

 tongue movements in the usual manner. Bateman 

 et at. (7) point out that, although some air is swallowed 

 as a side effect, there is no real evidence that the 

 sound is produced by eructation of air from the 

 stomach, as was maintained by earlier workers (1 18). 

 The esophagus behaves like a passive tube and it is 

 unnecessary to postulate any activity of its smooth 

 musculature. A modified technique making use of a 

 'buccal voice' has also been described (134). 



NECROLOGY OF SPEECH 



Speech involves a delicate coordination of phona- 

 tion, respiration, articulation and resonation. Its 



control may !»■ said to involve all components of the 

 motor svsicm pyramidal, extrapyramidal and cer- 

 ebellar together with those areas of the cerebral 

 cortex presumed (o subserve the functions of speech. 

 It is also likely that diencephalic mechanisms are 

 concerned in certain aspect-, of speech production, 

 more especially in governing speech rate and in 

 control of emotional expression. Possible neuro- 

 physiological relationships at the different levels of 

 speech control have been adduced by Husson (61) 

 and < rarde (40). 



Bulbai Syndromes 



The laryngeal muscles are supplied by the recurrent 

 branch of the vagus nerve, apart from the crico- 

 thyroid which is innervated by the external branch of 

 the superior laryngeal. The corresponding nuclei are 

 in the medulla. Nuclear and infranuclear lesions 

 produce varying degrees of laryngeal paralysis which 

 may or may not affect phonation. Thus a unilateral 

 lesion at am point between the nucleus ambiguus and 

 the recurrent laryngeal nerves causes a unilateral 

 paralysis of the vocal cords, with hoarseness and 

 difficulty in coughing but without loss of phonation. 

 If the lesion is bilateral, on the other hand, both cords 

 are paralyzed and phonation is abolished. In general, 

 lesions at the bulbar level affect phonation rather 

 than articulation, leading to changes in intensity and 



