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by Daniel Fink, MD, Chair, The Quiet Coalition
Restaurant noise is a problem for patrons trying to converse with their dining companions, and a common complaint in the Zagat survey.
When ambient noise is loud, people raise their voices to increase the speech to noise or signal to noise ratio to help others hear what they are saying. This creates a positive feedback loop, where everyone increases how loud they are speaking, until it’s so loud that no one can understand anything being said. The phenomenon, called the Lombard effect or cocktail party effect, has been known for a long time.
This study in the world’s most prestigious acoustical journal, the Journal of the Acoustical Society of America, adds to our knowledge of how restaurant noise affects understanding of speech. The researchers studied speech in a sound booth at different ambient noise levels. The sound level of speech increased as ambient noise increased. Subjects reported disturbance of speech beginning at 52.2 A-weighted decibels (dBA), with vocal effort beginning to increase at 57.3 dBA. The researchers noted that as background noise increased, it triggered a decrease in the willingness to spend time and money in a restaurant. The researchers concluded that restaurants should have ambient noise levels of 50-55 dBA. That’s a much lower sound level than that in most restaurants.
The study is quite technical, and I have two quibbles with it.
First, it was done in a sound booth. That is ideal for research, but I would be interested to see the study replicated in a real or simulated restaurant environment.
Second, the average age of the subjects was 21, with a range from 18-28. I would like to see the study repeated, even with the same methods, in a population age 58-68, with an average age of 61, or even 68-78, with an average age of 71.
I suspect the findings would be similar, but the decibel numbers would be significantly lower.
