0438 SNORE SOUND ANALYSIS: WITHIN AND BEYOND HUMAN HEARING RANGE

• Published in: Sleep (New York, N.Y.) N.Y.), 2017-04, Vol.40 (suppl_1), p.A163-A163
• Main Authors: Markandeya, MN, Abeyratne, UR
• Format: Article
• Language: English
• Subjects: Sound
• ISSN: 0161-8105; 1550-9109
• DOI: 10.1093/sleepj/zsx050.437

Abstract Introduction: Maximum hearing range experienced by the young child is 20Hz-20 kHz. Average middle aged adults can only hear the sounds of frequencies up to 15 kHz. Snoring is considered as a hallmark of an OSA disease. The acoustic analysis of snoring sounds has been developed as a promising tool in order to objectively evaluate snoring sounds. This study explores snore sounds from 4Hz to 35 kHz and in particular focuses on the non-human hearing component, i.e.15–35 kHz band. During an apnea event when Upper airways (UA) are fully collapsed, a large pressure difference can generate at the site of the collapse. Mechanical resistance of UA muscles may add some delay to the process of reopening of UA. The generated large pressure difference squeezes air through the narrow opening of UA. We hypothesise that the sound produced during such a condition covers broad spectrum possibly going beyond human hearing range. Methods: The snore sound data were recorded from six (Apnea Hypopnea Index range= 4.1 - 122.2) subjects undergoing polysomnography (PSG) test. Snore sound data were acquired with a free-field, condenser microphone. We explored the time domain response of snore sounds in multiple frequency bands covering the range 4Hz to 35 kHz. The response of snore sounds during various respiratory events was analysed by synchronising 15–35 kHz band of snore sound data with the flow and nasal pressure channels from the PSG data. Results: We analysed time domain response of 600–3000 snore episodes from each subject. The results of this analysis suggest that post-apneic/hypopneic snore episodes covers broad frequency range and show better existence beyond 15 kHz compared to non-apneic, pre-apneic and hypopneic snore episodes. Snore sounds analysis during respiratory events like breathing, flow limitation, hypopnea and apnea suggest that with an increase in the level of obstruction in the UA, causes airflow and nasal pressure to drop and showing the better existence of snore sounds in 15–35 kHz. Conclusion: This study shows that snore sounds of obstructive sleep apnea subjects exist outside the human hearing range. Support (If Any): None.