Quality analysis of laryngography in a busy hospital ENT voice clinic.

The Portable Laryngograph provides a non-acoustic plot of wet mucosal contact at the glottis over the vocal fold vibrational cycle called the Lx waveform in Laryngograph terminology. Although well-equipped clinics gain most ENT requirements for investigation from the video endoscope, the nature of stroboscopy prevents the investigation over single glottal periods and many transitory problems may be missed. A high-quality Lx signal waveform will reflect any irregularities in mucosal contact and substantially complements the endoscopy examination. Yield, however, is a problem in the environment of an ENT hospital voice clinic. In this topic paper the criterion of maximum acceptable normalised noise energy (NNE) = -15 dB is used to assess the quality of 61 Laryngograph measurements. By this criterion a pass rate of 78% was achieved. This is considered to be good within an ENT voice clinic population where voice problems are in fact the dominant reason for referral.