The study comes from Michael Miller, MD, director of preventive cardiology at the University of Maryland. Miller reported the findings at this week's annual meeting of the American Heart Association in New Orleans.

Ten volunteers identified specific music that made them feel a sense of joy. While the music played, Miller and colleagues used an ultrasound device to measure how well each person's blood vessels responded to a sudden increase in blood flow (caused by release of a blood pressure cuff).

When they heard joyful music, the volunteers' blood vessels dilated by 26% -- a very healthy response. It's similar in magnitude to the response seen after aerobic exercise.

Laughter also improved blood flow. After listening to a comedy tape, volunteers' blood vessels dilated by 19%. That's similar to the laughter effect seen in an earlier study, in which volunteers viewed excerpts from the comic movie Kingpin.

But music has a dark side, too. Listening to music that made volunteers feel anxious narrowed blood vessels by 6%.

"These results were music to my ears because they signal another preventive strategy that we may incorporate in our daily lives to promote heart health," Miller says in a news release.

Country music made most of the volunteers feel joyful. Heavy metal music made most of them feel anxious. But Miller says what matters isn't the type of music, but an individual's emotional response to the music.

Miller says that 10 different individuals might well have found different types of music joyful -- and heart healthy.

Funding for the study came from the American Heart Association, the Veterans Administration, and the National Institutes of health.