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Frequency spectra of normal breath sounds in childhood
H A Hidalgo1, M J Wegmann, W W Waring
1Department of Pediatrics, Tulane University Medical School, New Orleans.
Insights
Normal breath sounds in children change with age, differing significantly from adult lung sounds. These age-related variations in frequency content are linked to height and age, impacting clinical auscultation findings.
Area of Science:
- Pediatric Pulmonology
- Acoustic Physiology
- Respiratory Medicine
Background:
- Clinicians observe variations in children's breath sound frequency with age.
- Previous systematic documentation of these age-related changes in breath sounds is lacking.
Purpose of the Study:
- To investigate age-related differences in the frequency content of normal inspiratory breath sounds.
- To systematically document how breath sound frequency varies across pediatric age groups and in adults.
Main Methods:
- Recorded and analyzed inspiratory breath sounds from 35 children (0-13 years) and 5 adults (34-43 years).
- Utilized Fast Fourier Transform (FFT) to calculate average amplitude frequency spectrum (AFS) for each subject.
- Compared AFS shape and selected frequency parameters (F25, F50, F75, F95) between age groups.
Main Results:
- The AFS shape of the youngest children significantly differed from that of adults.
- Three frequency parameters (F25, F50, F95) showed significant differences between children and adults (p < 0.05).
- Parameters F25, F50, and F75 in children correlated with increasing height and age (p < 0.001).
Conclusions:
- Age-related differences in the frequency content of normal breath sounds exist between children and adults.
- These acoustic variations contribute to observable differences during clinical chest auscultation in pediatric populations.
Abstract:
Clinicians who auscultate the chest of normal children note that the frequency content of their breath sounds appears to vary with age. Because these changes have not been systematically documented before, we recorded and analyzed inspiratory breath sounds in 35 children (0 to 13 years) and five adults (34 to 43 years). Our objective was to determine if the frequency content of normal breath sounds differed with age. Using a Fast Fourier Transform program, we calculated an average amplitude frequency spectrum from the inspiratory portion of the breath sounds of each subject (n = 10 breaths), and we compared the shape of the AFS and the values of selected frequency parameters. We found that the shape of the AFS of the youngest children differed most from the AFS of adults. Three of four selected frequency parameters (F25, F50, F95) differed significantly between children and adults (p less than 0.05), and one parameter (F75) did not (p = 0.11). The F25, F50, and F75 parameters of children (but not F95) were correlated (p less than 0.001) with increasing height and age. These results suggest that differences in the frequency content of the normal breath sounds of children and adults contribute to the differences that clinicians detect during clinical auscultation.