Non-invasive photoglottography for use in the lab and the field

A non-invasive method of photoglottography is described that locates both light source and light sensor on the outside surface of the subject's neck. The study builds on the pioneering work of Honda, Maeda and colleagues, trying to overcome the problems of passing the light signal through the tissue of the neck twice. The specification of the light source and sensor have been improved, as has the optimal placement of the light sensor, now located centrally in the superior thyroid notch.