Acoustic and Perceptual Profiles of Swallowing Sounds in Preterm Neonates: A Cross-Sectional Study Cohort

Cervical auscultation, commonly used by speech-language pathologists in some countries as an adjuvant to the clinical feeding evaluation, requires data on acoustic and perceptual profiles of swallowing sounds. Whilst these exists in adults and children, none currently exist for preterm neonates. Our study aims to establish the acoustic and perceptual parameters of swallowing sounds in preterm neonates. Swallowing sounds were recorded on a digital microphone during oral feeding observations. Acoustic parameters of duration, peak frequency, peak power and peak intensity were determined. Perceptual parameters heard pre, during and post-swallows were rated as 'present', 'absent', or 'cannot be determined'. Eighty preterm neonates (43 males; mean age = 33.4 weeks [SD 2.6]) from three Australian special care nurseries demonstrated mean swallow durations of < 1 s. The peak amplitude correlated with the number of medical co-morbidities (r = 0.24; 95%CI 0.03-0.45). Most preterm neonates have coordinated swallows that are loud, quick and completed in < 1 s. The perceptual parameters of a bolus transit sound was consistently present in all preterm neonates. One in five pre-term neonates have an uncoordinated swallow where wheeze, stridor or wet breath sounds were present post-swallow. Our study provides clinicians with acoustic and perceptual parameters to guide use of cervical auscultation in special care nurseries. Future studies should consider simultaneous instrumental assessment to ensure validity when using cervical auscultation to support diagnostic decision-making on swallowing coordination.