Adductor spasmodic dysphonia (ADSD) can mimic the voice characteristics of muscle tension dysphonia (MTD) contributing to diagnostic confusion and inappropriate management. Elevated spectral noise has been reported in MTD, which may aid in differential diagnosis. The long-term average spectrum (LTAS) can be compared to a Gaussian bell curve using spectral moments analysis. Four moments describe features of the LTAS: spectral mean (moment 1), standard deviation (moment 2), skewness (moment 3), and kurtosis (moment 4). This investigation evaluated spectral moments analysis of the LTAS as an objective test to distinguish ADSD from MTD.