Acoustic rhinometry in pre-school children.

Acoustic rhinometry was performed in 35 normal nose-breathing children between 3 and 6 years. The average cross-sectional areas at the nasal valve, at the anterior end of the turbinates, and in the nasopharynx were 0.34 +/- 0.06 cm2, 0.35 +/- 0.08 cm2 and 1.37 +/- 0.48 cm2 respectively. The average minimal cross-sectional area was 0.29 +/- 0.06 cm2. The minimal cross-sectional area was located at the nasal valve in 14 and at the anterior end of nasal turbinates in 21 of the 35 children. As would be expected, the cross-sectional areas at different sites of the nasal cavity increased with increasing age of the children. But, whereas the minimal cross-sectional area increased by 0.024 cm2 per year, the nasopharyngeal cross-sectional area increased by 0.20 cm2 per year. No significant differences were found between boys and girls. Measurements of the posterior nasal and nasopharyngeal cross-sectional areas were unreliable, whenever the minimal cross-sectional area was less than 0.2 cm2. Furthermore, assessment of the nasopharynx may be difficult because of involuntary movements of the soft palate.