Agenda

MSc SS Thesis Presentation

• Thursday, 27 September 2018
• 10:00-10:30
• HB 17.150

Snoring Sound Production and Modelling; Acoustic Tube Modelling

The thesis project is aimed at designing an unobtrusive method to determine from snoring sounds the obstruction location and severity for persons that have benign snoring and that are residing in their natural sleep environment.

Similar to speech generation, which is enabled by opening and closing of the vocal cords, the sound of snoring consists of a series of impulses caused by the rapid obstruction and reopening of parts of the upper airway. By exploiting this similarity, we try to explain snoring sound production using analysis and synthesis techniques that have been applied to speech. In particular, 1-D tube models and linear prediction have been studied and employed. 

From a trial on anti-snoring device efficacy, audio recordings were available. These contained snoring sounds of multiple participants over multiple nights and were used for analysis. Similar to speech analysis, the Iterative Adaptive Inverse Filtering (IAIF) method has been used to find excitation flow and airway tract transfer functions from snoring sounds during the inhalation period. It has been found that the linear prediction part in IAIF is not suitable to directly determine the cross-sectional area of the upper airway from snoring sounds. 

A model has been built using acoustic tube theory with the purpose of reflecting the physical realities of the upper airways. The tube model allows modeling flow obstructions at arbitrary positions in the upper airways. The transfer spectra from the acoustic tube having obstructions at various positions can be compared to the tube model resulting from IAIF using a gain-independent Itakura Spectral Distance Measure and the best match can be determined. This alternative approach was found to indicate obstruction positions which vary over persons. Further research is required to establish if the thus determined locations are adequately matching the true snoring cause and constitute a viable way for generating advice for anti-snoring devices and measures.

Overview of MSc SS Thesis Presentation