Stop for a minute and listen to what is going on around you.

Maybe the television or the radio is on. Maybe your children are yelling at each other. Maybe the microwave is beeping, or your cell phone is ringing. Maybe you have a window open and you can hear the sounds of traffic or the songs of birds.

Our world is filled with sound, but we don't often stop to think about what it means. Joshua Leeds does. Leeds is an authority on psychoacoustics — the study of the effects of music and sound on the human nervous system.

"Sound," he says, "is a potent energy that should not be taken for granted." Over the past few decades, the San Francisco area-based researcher says, studies have found that sound particularly affects our human body pulses — brain waves, heart rate and breath. It does this, he says, through three specific processes: resonance (the ability of one vibration to alter another), entertainment (the ability of periodic rhythms to speed up or slow down our pulses) and auditory pattern identification (sending the brain into an active or passive mode).

But it is not only our human brain that reacts that way. Recently, Leeds and veterinary neurologist Susan Wagner have begun studying the effects of sound on dogs.

It all started, Leeds said in a telephone interview from his Bay-area home, when a pianist named Lisa Spector came to him. She also raised foster puppies for the Guide Dogs for the Blind program and had noticed that when she played certain music on her 9-foot Steinway, the rambunctious 16-week-old puppies would tumble under the piano and fall into a calm and gentle sleep. She asked Leeds about making an album of classical music for dogs.

At first Leeds was skeptical. He had visions of, as he says, "my reputation going to the dogs." But the more he looked into it, the more he became intrigued. And the more he researched, the more he began to believe that sound — particularly certain kinds of music — does affect other species.

He came across research by an Irish scientist named Deborah Wells, who had conducted a study in dog shelters and found that classical music created notable relaxation in canines, while heavy-metal music resulted in more agitated behavior.

Wells concluded: "It is well established that music influences our moods. Classical music, for example, can reduce levels of stress, whilst grunge music can promote hostility, sadness, tension and fatigue. It is now believed that dogs may be as discerning as humans when it comes to musical preference."

Leeds admitted he was still a little dubious. "I'd never seen a dog pant, tap a paw or wag a paw in rhythm. Would it be possible to change a dog's heart rate or brainwaves with the use of external rhythms?"