Inclusion Criteria:  Males and Females Aged 21-100 Scheduled for Botulinum Neurotoxin (BoNT) Treatment for Spasmodic Dysphonia (SD)  Exclusion Criteria:  Subjects who are Pregnant or Lactating Subjects with Compromised Renal or Cardiac Function Subjects with Spasmodic Dysphonia with Superimposed Vocal Tremor