Objective: The loud and severely distorting form of audible nasal emission (commonly known as nasal turbulence or nasal rustle) typically occurs with a small velopharyngeal opening during production of pressure-sensitive consonants. The purpose of this study was to determine whether bubbling of the secretions, which commonly occurs on the superior aspect of the velopharyngeal port when there is a small opening, is a periodic process that can generate sound in the nasal cavity.
Participants: Ten pediatric patients were included in the study. All participants had normal articulation and resonance but exhibited audible nasal emission characterized as nasal rustle.
Measures: For each participant, high-speed video (HSV) nasopharyngoscopy and acoustic signals were recorded simultaneously. The acoustic recordings were captured in a manner similar to nasometry using nasal and oral microphones connected to a separation plate. Spectral analysis of the audio recordings and the HSV images was used to determine correlation between the acoustic and visual measurements.
Results: This study showed that secretion bubbling is a periodic process and its frequency, measured from the HSV data, was also captured by the acoustic measurements. The nasal acoustic signal correlated more strongly with the video of bubbling than the oral acoustic signal in the majority of the cases where bubbling occurred.
Conclusion: These findings are strong evidence that secretion bubbling plays a significant role in the mechanism that generates undesired sound in the nasal cavity. Further work is needed to determine whether this sound is perceived as nasal rustle.
Keywords: high-speed videoendoscopy; mucus secretion displacement; nasal rustle; nasal turbulence; spectral characteristics.