\f7 But where was all this clamor coming from?
The researchers began at the pediatric ICU. Each bed was surrounded by beeping instruments with intrusive pumps or blasts of warning signals. Overhead, the sound of doctors and nurses being paged added to the ambient noise, not to mention the ongoing conversation among doctors, nurses, patients, families, orderlies and other staff members -- each trying to speak just a little bit louder to be heard.
Busch-Vishniac describes the phenomenon as the "cocktail party effect," in which everyone incrementally speaks more loudly to be heard as the noise level around them increases.
Her colleague West, professor of electrical and computer engineering, says that this process of gradually talking louder is exhausting for speaker and listener alike. "Having to talk louder and having to be more attentive just to listen to others is considered one of the reasons that hospital staff suffers from fatigue," he says.
Blood pressure rises
Patients simply longing for a decent night of sleep suffer as well. Even though fewer people populate the hospital's halls at night, the combination of the powerful hospital ventilation system and alarm-laden electronic devices throughout still makes a hospital bear more resemblance to a 24-hour shopping mall than a quiet place where people can heal.
The serious and specific health risks of noise were examined in two other studies published this month. A University of Michigan study in the Archives of Environmental Health suggests that working in loud places can increase blood pressure levels. And another study of more than 4,000 cardiac patients, published in the European Heart Journal -- Europe's leading cardiac journal -- linked exposure to chronic noise with an increased risk of heart attacks.
In the blood pressure study, Michigan researchers studied workers in a Midwest auto assembly plant and looked at different types of noise in the factory setting. Continuous or "usual" noise was recorded at between 42 and 103 decibels. Elevated noise ranged between 46 and 124 decibels, and spikes in instantaneous loud noises went from 113 to 145 decibels.
The researchers gave factory workers mobile monitors that took blood pressure readings every 10 minutes and recorded noise levels every minute throughout the day.
