[Unusual causes of biphonation]

Area of Science:

• Laryngology
• Speech and Hearing Science
• Vocal Fold Physiology

Background:

• Biphonation, or diplophonia, is a voice disorder characterized by the production of two distinct pitches simultaneously.
• While beneficial in some animal vocalizations, it is typically perceived as undesirable roughness in human speech.
• Understanding the diverse mechanisms of biphonation is crucial for accurate diagnosis and effective treatment.

Observation:

• This study details two uncommon cases of biphonation in human patients.
• Case 1 involved a patient with vocal fold bamboo nodes, causing asynchronous vibration patterns.
• Case 2 presented a patient with post-surgical vocal fold mucosal fixation, creating dual vibrating segments.

Findings:

• Vocal fold bamboo nodes can disrupt normal vibration, leading to intermittent anterior-posterior vocal fold movement and biphonation.
• Surgical interventions, specifically pitch-raising procedures, can result in mucosal fixation and the formation of separate vibrating zones (neo-glottides).
• These findings highlight novel structural abnormalities as direct causes of biphonation.

Implications:

• The identification of these unusual mechanisms broadens the differential diagnosis for biphonation.
• This research may inform surgical techniques and post-operative care to prevent such complications.
• Improved understanding can lead to more targeted therapeutic strategies for patients experiencing voice disorders like biphonation.