Related to Material relating to the development and use of stroboscopes before c.1910
Description:

'The Position and Condition of the Vocal Lips in the Chest and Head Registers.

Dr. JOBSON HORNE, on behalf of Dr. Musehold, of Berlin, showed a series of photographs of the larynx demonstrating the above conditions. Dr. Home referred to the researches of Dr. Musehold, and drew attention to what he understood from Dr. Musehold to be the more important conclusions which had been arrived at with the help of the stroboscope, and which the photographs demonstrated.

In the chest register it was seen that the glottis is "opened and shut," whereas in the head register it is "widened and narrowed," a difference still more demonstrated with the stroboscope.

The cords themselves in the chest register, and more particularly in the production of loud chest-notes, showed a rounded or tumid form. This was accounted for by the expiratory current of air meeting with an increased resistance, and forcing the cords upwards; and it was the analogy of this condition of the cords with the condition of the lips when applied to the mouth-piece of a trumpet in producing loud notes that suggested the term "vocal lips " in the present instance.

The photographs further showed that the deposition of the mucus secreted on to the cords was along different lines in the two registers; this was attributed to a difference in the manner and intensity of the vibrations.

For a more detailed description of the photographs, and of the photographic apparatus and stroboscope used, Dr. Home referred to Dr. Musehold's paper which had recently appeared in the " Archiv für Laryngologie und Rhinologie."' (131)