The acoustics of obstructive sleep apnea: a study of the over all sound pressure level during obstructive apnea events

Obstructive sleep apnea syndrome (OSAS) is a sleep disorder where a person stops breathing for a period of time due to an anatomical obstruction of the upper airway while sleeping. The most common characteristic of persons with OSAS is snoring. The investigation being reported attempted to find a correlation between the over all sound pressure level (OASPL) of the sounds of snoring and the obstructive apnea events. The procedure involved recording the OASPL onto a polysomnograph with an instrumentation quality sound level meter (SLM) placed above the patients head while the patient slept. The signal was processed by a voltage converter which had a logarithmic output of the true root mean square (RMS) voltage from the SLM. The investigation showed a wide variation in the characteristics of the OASPL time history curves for each patient and significant differences were found between patients. No reliable diagnostic algorithm based on OASPL could be obtained.