Does the vesicular lung sound come only from the lungs?

Area of Science:

• Respiratory acoustics
• Pulmonary physiology
• Bioacoustics

Background:

• The frequency spectrum of normal lung sounds is poorly understood, particularly in the lower frequency ranges.
• Previous research reports varying peak intensity frequencies (10-200 Hz) for lung sounds.
• The potential contribution of musculoskeletal sound to inspiratory lung sounds remains unassessed.

Purpose of the Study:

• To differentiate lung sounds from sounds generated by muscular contraction.
• To analyze the frequency components of normal lung sounds during various respiratory maneuvers.
• To investigate the impact of musculoskeletal activity on lung sound characterization.

Main Methods:

• Frequency analysis of sounds during normal inspiration.
• Analysis of sounds during pre-inspiration and post-inspiration open-glottis breath-holds.
• Comparison of sound spectra between lung-generated and musculoskeletal-generated sounds in 4 healthy subjects.

Main Results:

• Musculoskeletal sound components increased significantly as lung sound components decreased at frequencies below 200 Hz.
• At frequencies of 50 Hz and below, inspiratory sounds and post-inspiratory breath-hold sounds were nearly indistinguishable.
• This indicates substantial overlap and contamination of lung sounds by musculoskeletal noise.

Conclusions:

• Musculoskeletal noise significantly contaminates traditional assessments of normal lung sound.
• Lower frequency components (<200 Hz) of recorded lung sounds are heavily influenced by muscle activity.
• Further research is needed to refine methods for isolating true lung sound components.