Slurred Speech—Is It a Reliable Indicator?

Slurred Speech—Is It a Reliable Indicator?

Slurred speech is considered a classic sign of alcohol impairment. But is it a reliable indicator? Your Orange County DUI attorney is well-versed in the details of this commonly used observation. It turns out that defining and characterizing slurred speech is quite subjective.

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One study made audio recordings of men talking while sober, then made recordings of the same men repeating the same utterances after drinking. Listeners, including college students and Indiana state troopers, compared the matched pairs of statements to judge whether the subjects were sober or intoxicated. The results came out as expected and listeners correctly detected the changes in speech patterns. But not all studies are as predictable.

Another research study on the topic tested subjects at various Blood Alcohol Concentration (BAC) levels including sober and four increasing BAC levels. As expected, the experiment showed changes in speech with greater alcohol consumption. Yet the researchers noted that about one-fifth of subjects did not have slurred speech after drinking.

Listening for Clues

The other half of this experiment focused on the listeners—were they able to correctly evaluate and identify slurred speech? This part of the research was done with actors who repeated specific controlled utterances in different situations: simulated alcohol effects, actual intoxication, and when attempting to sound sober at a high BAC level.

What did the listeners think? As it turns out, they rated the highest drunkenness score when the actors where actually sober but simulating alcohol effects. This higher score was recorded 88 percent more often than when the actors were really intoxicated. Another study revealed that about 60 percent of the time, listeners rated the actors as less intoxicated than they really were.

An investigation of the Exxon Valdez studied the captain’s voice recordings made prior to the Alaska accident. Speech analysis before, during and after the incident found changes in Captain Hazelwood’s speech. But the study authors said the acoustic-phonetic recordings were limited and it was difficult to draw inferences about the captain’s state.

The bottom line in these and other studies is that research is inconclusive about the relationship between speech and intoxication. Drawing conclusions from statistical analysis of speech patterns may be impractical and particularly difficult at low levels of BAC.

If you were arrested for DUI and your speech pattern was a factor, it’s important to call an Orange County DUI attorney who is aware of the latest forensic findings related to slurred speech and other tests. Call Coffey & Coffey today at (800) 706-7888 for more information.