Human forced expiratory noise. Origin, apparatus and possible diagnostic applications

Area of Science:

• Bioacoustics
• Respiratory Physiology
• Medical Instrumentation

Background:

• Forced expiratory (FE) noise, including forced expiratory wheezes (FEWs), is a bioacoustic signal reflecting human lung biomechanics.
• FE respiratory noise originates from acoustic and hydrodynamic mechanisms within the bronchial tree.
• Mid-frequency FEWs (400-600 Hz) are linked to lower bronchial levels (0-3rd), while high-frequency FEWs (>600 Hz) originate from higher levels (2nd-6th).

Purpose of the Study:

• To develop and validate a novel acoustic method for assessing human lung function.
• To analyze forced expiratory noise signals using a new approach focusing on FE time and band-pass energy.
• To evaluate the potential of this technique for monitoring respiratory health in various conditions, including extreme environments.

Main Methods:

• Development of a laboratory prototype apparatus including an electret microphone sensor, stethoscope head, laptop with external sound card, and specialized software.
• Application of a new signal analysis method evaluating forced expiratory time (200-2000 Hz) and energy in 200-Hz bands, instead of direct forced expiratory wheeze measures.
• Experimental validation comparing developed acoustic parameters with standard lung function indices from spirometry and body plethysmography.

Main Results:

• Developed FE acoustic parameters demonstrate correspondence with basic lung function indices obtained via spirometry and body plethysmography.
• The new acoustic method shows potential sensitivity to respiratory deviations, possibly exceeding conventional methods in some cases.
• Preliminary results indicate the technique's viability for acoustic monitoring of lung function in extreme conditions like diving and space flight.

Conclusions:

• The developed acoustic technique offers a promising, non-contact method for monitoring human lung function.
• This approach reduces the risk of respiratory cross-contamination, enhancing safety in clinical and field settings, particularly relevant post-COVID-19.
• The non-invasive nature and potential for increased sensitivity make this technique valuable for diverse applications, from routine check-ups to specialized environments.