Objective:
Anterior glottoplasty is a common pitch-elevating phonosurgery for transgender voice feminization and functional dysphonia. This study aimed to evaluate how varying degrees of anterior–posterior vocal fold shortening affect phonatory function using an ex vivo canine laryngeal model.

Methods:
Excised larynges from adult Chinese rural dogs were prepared into anatomically intact models. The anterior vocal folds were sutured to simulate anterior commissure glottoplasty with shortening ratios of 0%, 10%, 20%, 30%, 40%, and 50%. Fundamental frequency (F0), sound pressure level (SPL), phonation threshold pressure (PTP), phonation threshold flow (PTF), and phonation threshold power (PTW) were measured under each condition.

Results:
Under different vocal fold shortening range conditions, F0, SPL, PTP, PTF, and PTW all showed significant differences (P < 0.05). F0 exhibited a gradual upward trend with increasing shortening range, rising from 233.0 ± 35.81 Hz at 0% to 378.03 ± 44.69 Hz at 50%, with statistically significant differences between the 30% and 40% groups (P < 0.05). SPL exhibited a gradual downward trend with increasing shortening range, decreasing from 73.00 ± 5.66 dB at 0% to 53.4 ± 4.06 dB at 50%, with statistically significant differences between the 30% to 40% and 40% to 50% groups (P < 0.05). PTP increased with the shortening range, rising from 1.01 ± 0.21 kPa at 0% to 2.75 ± 0.40 kPa at 50%, with statistically significant differences between all groups except 10% and 20% (P < 0.05). PTF increased from 2.03 ± 0.22 L/min at 0% to 3.63 ± 0.33 L/min at 50%, with statistically significant increases between the 10% to 20% and 20% to 30% groups (P < 0.05). PTW showed the most significant increase, from 2.05 ± 0.52 L·kPa/min at 0% to 10.04 ± 1.96 L·kPa/min at 50%, with statistically significant increases between all adjacent groups (P < 0.05). Compared to F0, the upward trend of PTW from 30% to 50% was more pronounced.

Conclusion:
Anterior–posterior shortening strongly influences pitch elevation in anterior commissure glottoplasty. Excessive shortening markedly increases phonatory effort and decreases sound intensity, highlighting the need to balance pitch elevation with phonatory efficiency in surgical design.