Frequency analysis of snoring sounds during simulated and nocturnal snoring.

Despite several ways of investigation, such as clinical examination, drug-induced sleep endoscopy and pressure measurement of the upper airway, it is still difficult to locate the site of snoring exactly. Frequency analysis of snoring sounds is described as a promising diagnostic tool. The aim of the study was to examine simulated snoring under conditions awake, record the produced snoring sounds and compare those sounds with nocturnal snoring. A total of 50 snoring male patients were examined clinically by flexible nasal endoscopy and simulated snoring under conditions awake, and the simulated snoring sounds were recorded. Additionally, nocturnal snoring sounds were recorded during nighttime polysomnography. Snoring events were analyzed by fast-fourier-transformation and the intensity peaks 1-5 were evaluated. Rhythmic and non-rhythmic snoring events were distinguished depending on present obstructive apneas. Clinical and polysomnographical data were correlated with the results of the frequency analysis of the snoring sounds. Simulated snoring sounds revealed a low frequency of 200 Hz in intensity peaks 1 and 2 with an increase up to 3,000 Hz in peaks 3-5. Similar frequency patterns were detected in rhythmic nocturnal snoring. Non-rhythmic snoring events revealed frequency patterns between 2,000 and 3,000 Hz in all five intensity peaks. Simulated snoring resembles rhythmic nocturnal snoring with low-frequency intensity peaks, whereas non-rhythmic snoring revealed high frequencies. The examination during simulated snoring and frequency analysis of snoring sounds might contribute in locating the pathogenesis of snoring.