High frequency region of the snore spectra carry important information on the disease of sleep apnoea

Abstract

Snoring is the most common symptom of obstructive sleep apnoea (OSA). Several researchers have reported differences between the power spectra of non-OSA and OSA snorers. The traditional approach over the years has been to record snore sounds at a bandwidth of < 5 kHz. Narrowing of the upper airways during OSA events and the resulting upward shift of snore frequencies also lend support to the idea of examining snore sounds beyond 5 kHz. In this paper, we compute the power spectra of snores in three different bands defined as: low-frequency band (LFB: < 5 kHz); middle-frequency band (MFB: 5–10 kHz) and high-frequency band (HFB: 10–20 kHz). We illustrate that there is a significant difference between non-OSA snorers (Apnoea Hypopnoea Index (AHI) < 10) and OSA snorers (AHI > 10) in the region > 5 kHz. We then develop a feature to diagnose OSA based on the spectral differences in the high frequency region and evaluate its performance on a database of 20 subjects. Our results strongly suggest that the high-frequency region of the snore sounds carry information, hitherto disregarded, on the disease of sleep apnoea.

Keywords::

• Obstructive sleep apnoea
• Snoring
• High frequency region

Acknowledgements

Thanks to the Australian Research Council for supporting this work under grant no: DP0773687 to Dr Abeyratne. Dr Emoto is also director of Grants-in-Aid for Scientific Research #21700509 from Japan Society of Promotion of Science (JSPS).

Declaration of interest:The authors report no conflicts of interest.