Introduction: Adductor spasmodic dysphonia (ADSD) is characterized by involuntary laryngeal muscle spasms. Due to the lack of a quantitative evaluation method, most measurements have demonstrated difficulty in validity and reliability for diagnosing ADSD. This study aimed to establish a novel indicator for ADSD and determine its diagnostic effects. Methods: We investigated 98 voice samples from 49 patients with ADSD and 49 healthy participants. A sustained vowel was recorded by a high-definition audio recorder. Voice samples underwent regular acoustic evaluation and a novel global dimension (GD) method. GD, Jitter, Shimmer, HNR, Frequency shift, and CPPS were measured for both groups. Results: Statistical analysis revealed that the GD method effectively differentiated ADSD patients from healthy participants (p < 0.001, D′>0.8). Subsequent multiclass receiver operating characteristic analysis demonstrated that GD possessed the most significant classification accuracy (area under the curve = 0.988) compared with other acoustic parameters. Conclusion: GD was an effective metric for objective differentiation between ADSD patients and healthy participants. This metric could assist clinicians in the diagnosis of ADSD patients.