Snoring sound intensity study with ambient and tracheal microphones

Snoring sound intensity is an index of the disturbance level caused by the snoring phenomenon. Snore intensity is usually calculated from the ambient sound signal by means of an analogue sound analyser. The snoring sound can also be acquired with a microphone placed on the trachea. In this study, an algorithm is proposed to calculate the snoring intensity from both ambient and tracheal snoring sound signals. The algorithm was validated by a calibrated sound source. It was applied to study the relationship between ambient and tracheal snoring intensity, both in simulated snores from volunteers and in real recordings from simple snorers and obstructive sleep apnea syndrome patients. Linear correlation coefficient, linear regression line and quadratic polynomial fit between ambient and tracheal snore intensity values were explored. Ambient snore intensity was found to be predictable from tracheal snore intensity by a simple regression line with rather good accuracy.