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IOWA ACADEMY OF SCIENCE Voi.. XXVII, 1920 
WHAT CONSTITUTES VOICE? 
C. I. ERICKSON 
I. General mechanism of voice production- — 
A. Physiological 
1. Eungs 
2. Larynx 
3. Resonating Cavities 
a. Ventricles of the Larynx 
b. Lower pharynx 
c. Upper pharynx 
d. Oral cavity 
e. Nasal cavity 
f. Sinuses 
4. Muscles 
a. Ten expiratory muscles 
b. Laryngeal muscles 
(1) Five intrinsic 
(2) Four extrinsic or infrahyoid 
c. Supra-laryngeal muscles 
(1) Five pharyngeal 
(2) Four suprahyoid 
(3) Four maxillary 
(4) Eight lingual 
(5) Ten labial 
(6) Five palatal 
(7) Five nasal 
B. Psycho-physical 
1. Auditory imagery and sensations 
2. Kinaesthetic imagery and sensations 
3. Tonal memory 
II. Basic factors — 
A. Pitch — 'its primary mechanism of control 
1. Physiological 
a. Vocal cords — variable as to weight, length, shape, tension, 
and condition 
b. Intrinsic laryngeal muscles 
c. Supra-laryngeal muscles 
2. Psycho-physical 
a. Pitch discrimination 
B. Intensity — its primary mechanism of control 
1. Physiological 
a. Lungs variable as to capacity and condition 
b. Resonating cavities — variable as to number used, size, 
shape, condition 
c. Expiratory muscles 
d. Supra-laryngeal muscles 
2. Psycho-physical 
a. Intensity discrimination 
b. Acuity of hearing 
