The perception, generation, and delivery of speech involves about 67 percent of the cerebral functions and about 140,000 synchronized neuromuscular events per second. The Hayre Impairment Measure is a quantitative measure of drug consumption obtained from a subject's speech. The measure is derived from the time and frequency representation of spoken numerical digits. It is the only drug consumption analysis method that yields the true impairment of a subject at the time of examination and is not a secondary chemical measure. Initial research for the Hayre Impairment Measure was conducted on subjects charged with drunk driving offenses. All the subjects were determined by a breathalyzer to have blood-alcohol concentrations above 0.1. Their spoken digits were recorded by the arresting officers and analyzed by the author (Hayre). The voice impairment data were cross-correlated. In all cases, the subjects were found to be impaired, but the impairment levels did not vary linearly with the breathalyzer results. This was expected, since the breathalyzer cannot account for the time elapsed since the subject drank the alcohol, the amount of food consumed, the subject's drinking habits, the tolerance level of the subjects, body weight, and other factors. 18-item bibliography.