A decreased volume of voice and a marked narrowing of the vocal register by recurrent nerve paralysis as well as a loss of vocal cord tension and a phonetic disturbance in high-pitch voice by superior laryngeal nerve paralysis were noted in our experimental and clinical observations in the larynx of dogs and human subjects, In most of these cases, the unilateral vocal cord was found to be fixed in paramedian position, but the bilateral vocal cords became fixed in cadaver's position when the bilateral laryngeal nerve paralysis supervened or the external laryngeal muscles were removed. This fact is considered to be indicative that the external laryngeal muscles and the compensatory working of the contralateral laryngeal nerve have a great influence upon the voice and the status of vocal cord.
Phonetical investigations in the waste of air, the volume of voice, the vocal register and the tone of voice in a variety of vocal cord diseases enabled the author to assume the status of vocal cord and its mode of vibration corresponding to a certain kind of voice.
Sonographical examination of the voice of vowel“A”revealed that phonetic disturbance in the component resonance ranging from fundamental to 1000cps and in the neighborhood of 4000cps was the decisive factor in the cause of a hoarse voice and the abnormal voice which was chiefly encountered on vocal register change.
