The effect of alcohol on central auditory processing (comparison with marihuana).

Twelve subjects between the ages of 23 and 62 were tested for changes in hearing acuity and dicrimination after ingestion of four ounces of vodka (80 U.S. proof = 40 per cent ethyl alcohol). As compared with their own pre-alcohol ingestion test results, these subjects revealed, 1) a decrease in discrimination of speech on CID W22 lists under difficult listening conditions, (in quite at 10 dB SL and in noise at a signal-to-noise ratio of -6); and 2) a decrease in performance on a filtered speech test low-pass, high-pass, and binaural fusion. The staggered spondaic word test was moderately affected only in one of the 12 subjects. Pure toe thresholds, speech reception thresholds, and speech discrimination, at 40 dB SL were not influenced. It was concluded that alcohol ingestion in moderate amounts alters the central auditory processing under difficult listening conditions. When compared with a previous study using marihuana, it was found that the discrimination ability was reduced by alcohol ingestion while marihuana significantly improved speech discrimination.