Tracheal Sounds Features Changes in Different Sleep Stages Based on Complex Wavelet Analysis

Area of Science:

• Biomedical Engineering
• Sleep Medicine
• Signal Processing

Background:

• Breathing sound analysis during sleep offers insights into upper airway function.
• Sleep stages can alter respiratory sound characteristics.
• Understanding these alterations is crucial for diagnosing sleep-related breathing disorders.

Purpose of the Study:

• To investigate the relationship between tracheal breathing sound features and different sleep stages.
• To determine if sleep stage affects complex Gaussian wavelet coefficients of breathing sounds.
• To establish a method for differentiating sleep stages using respiratory acoustic signals.

Main Methods:

• Recording tracheal breathing sounds from 5 individuals during sleep.
• Calculating complex Gaussian wavelet coefficients for the deceleration phase of approximately 3000 breath cycles.
• Segmenting recordings into 30-second episodes and labeling them with corresponding sleep stages.
• Analyzing the Mahalanobis distance of wavelet coefficients against reference distributions for each sleep stage.

Main Results:

• The Mahalanobis distance between real parts of complex Gaussian wavelet coefficients and reference distributions showed consistent changes across different sleep stages.
• Specific patterns in breathing sound features were observed to correlate with distinct sleep stages.
• The analysis demonstrated a quantifiable difference in acoustic markers related to sleep stage.

Conclusions:

• Tracheal breathing sound analysis, utilizing complex Gaussian wavelets, can effectively differentiate between sleep stages.
• The observed changes in wavelet coefficients provide a potential biomarker for upper airway status during sleep.
• This non-invasive method holds promise for sleep monitoring and the detection of sleep-related breathing abnormalities.