Comparison of snoring sounds between natural and drug-induced sleep recorded using a smartphone

Snoring is an important clinical feature of obstructive sleep apnea (OSA), and recent studies suggest that the acoustic quality of snoring sounds is markedly different in drug-induced sleep compared with natural sleep. However, considering differences in sound recording methods and analysis parameters, further studies are required. This study explored whether acoustic analysis of drug-induced sleep is useful as a screening test that reflects the characteristics of natural sleep in snoring patients.

The snoring sounds of 30 male subjects (mean age=41.8years) were recorded using a smartphone during natural and induced sleep, with the site of vibration noted during drug-induced sleep endoscopy (DISE); then, we compared the sound intensity (dB), formant frequencies, and spectrograms of snoring sounds.

Regarding the intensity of snoring sounds, there were minor differences within the retrolingual level obstruction group, but there was no significant difference between natural and induced sleep at either obstruction site. There was no significant difference in the F₁ and F₂ formant frequencies of snoring sounds between natural sleep and induced sleep at either obstruction site. Compared with natural sleep, induced sleep was slightly more irregular, with a stronger intensity on the spectrogram, but the spectrograms showed the same pattern at both obstruction sites.

Although further studies are required, the spectrograms and formant frequencies of the snoring sounds of induced sleep did not differ significantly from those of natural sleep, and may be used as a screening test that reflects the characteristics of natural sleep according to the obstruction site.