Effects of Increased Nasal Volume due to Topical Adrenaline on the Voice

Resonance properties of the nasal and sinus cavities are involved in the individuality of speech. However, detailed information on how alterations in the nasal cavity morphology affect voice quality is lacking. The aim of the present study was to investigate the effects of structural changes in the nasal cavity on voice production by spraying a topical adrenaline solution with a vasoconstrictive effect into the nasal cavity, causing nasal mucosal contraction. Prospective. Overall, 51 adult volunteers were recruited from the Otorhinolaryngology Outpatient Department of the Jikei University Hospital from June to September 2022. Among them, 20 completed acoustic rhinometry and voice recordings before and after adrenaline spraying. The nasal consonant [N] uttered with the mouth completely closed was recorded for 5 seconds. The remaining 31 volunteers completed all auditory experiments. This was conducted to determine whether the changes in voice before and after adrenaline spraying could be discriminated against by the participants. The nasal volume had increased 5 and 10 minutes after spraying compared to that before spraying, reaching a significance at 10 minutes (P = 0.06). It had increased at 2 and 5 cm from the external nostrils compared to that within 3 cm of the external nostrils (P = 0.04). Among the 31 volunteers in the auditory experiments, 30 had a discrimination rate >90%, with a mean of 96.3% (standard error, 3.2). The spectral envelope of the 16 frequency bands varied significantly at 500-Hz increments (P = 0.0006). In particular, changes in the high-frequency bands were larger between 4500 and 6000 Hz. Nasal enlargement with 0.02% topical adrenaline affects the spectral envelope, particularly in the high-frequency bands between 4500 and 6000 Hz, and perceptibly alters the voice.