I grew up in a home that was within earshot of railroad tracks. As a young boy, I had a fanciful notion about what the sound of the choo-choo going by meant. I thought the train was rising in the air and taking off like an airplane as the pitch went higher, then landing out of town as the pitch became lower again.

This erroneous thinking had a lot to do with being a kid, of course, and not understanding the physics of sound waves. But not being able to see the choo-choo also contributed to my incorrect assessment. My gravity-defying train was an early lesson in how our interpretation of sound depends on the setting, as well as the input—or lack of it—from our other senses.

Who Said That? The Illusion of Ventriloquism

Ventriloquism is a classic example of not always being able to trust what we think we hear. Even though we know the ventriloquist is doing the talking, we still feel that the voice is coming out of the dummy’s mouth. Why is this? Because our brain is always working to make sense of our world, and will make the most logical interpretation based on the information we have. It doesn’t make sense that the ventriloquist is talking if his lips aren’t moving. It does make sense for spoken words to be coming from a mouth that is opening and closing. The illusion is complete.

Volume and pitch can also be manipulated to fool the listener. If a humming person who is standing still gradually hums louder and at a higher pitch, somebody facing away from him in the distance will most likely think he’s coming closer.

Numerous experiments have also shown that sound can alter perception of moving objects even when you can see what’s happening. In a 2005 study conducted by Adam Hecker and Laurie Heller of the Department of Cognitive and Linguistic Sciences at Brown University, using different sounds to accompany an animated moving ball had a major effect on what people thought they saw. When the ball movement was accompanied by a rolling sound, 80% of observers said the balls were rolling. When the accompanying sound was that of a bouncing ball, only 20% of the listeners said the ball was rolling. The researchers also showed that sound influences perception of speed. When videos of a ball moving at the same speed were accompanied by either bounce or roll sound effects, most observers said the ball with the roll audio was moving faster.

Manipulation of sound to affect perception is, of course, standard procedure for moviemakers. They use sound to make the action seem faster or a scene more frightening, sad, or humorous than it would be in real life. Many of us are manipulated by these tricks even when we know we’re being manipulated.

Perception of Sound and Survival

Our brains are always adjusting our reactions to sounds. If they didn’t, we’d be overwhelmed in a hurry. Imagine if a cow’s moo continually startled a farmer. Or if a city dweller froze every time she heard a car horn. Our stress levels would be perpetually at high alert if we granted all sounds equal status. With experience we learn to differentiate bad noise from good noise. We take cover when we hear an explosion, and we rush to our seats when the featured attraction at a concert starts warming up. We also learn to stay calm when sounds are neutral and have no connection with adverse events.

Problems arise when we are conditioned to fear a certain sound even when it poses no threat. Soldiers with battlefield experience can develop a negative association with any sound resembling an explosion or gunfire; a backfiring car or thunder can cause some veterans to shiver in fear. Researchers have found that fear itself can decrease our ability to differentiate sounds according to their context, which is a hallmark of post-traumatic stress disorder.

Certain types of sounds also have therapeutic value, especially for alleviating anxiety. In a study commissioned by Spotify, the digital music service, anxiety psychologist Dr. Becky Spelman of the Private Therapy Clinic in London and her research team investigated music’s ability to relieve anxiety, especially flight anxiety. She discovered that music with a rhythm of 60 beats per minute combined with slow, rhythmic breathing helps lower heart rate and blood pressure, which in turn helps reduce anxiety. Listening to this music with headphones increases the therapeutic effect because it stimulates both sides of the brain.

“Travel anxiety is caused by irrational thoughts, where the threat is exaggerated and inappropriate,” notes Dr. Spelman. “Music that stimulates both the logical left and emotional right sides of the brain is said to stimulate the limbic system, which processes negative memories and emotions, which in turn helps people think in a more balanced, rational way, suppressing anxiety.” (Here is Spotify’s playlist, Calming Music to Fly To, based on Dr. Spelman’s research.)

Music and Emotion: A Complicated Relationship

The power of music to create different moods is another demonstration of how important a role sound plays in our lives. As we know from movies, music can trigger feelings of jubilation, sadness, and everything in between. It can impart a sense of danger to a scene of everyday life or make a casual walk in the park seem comical.

But it’s a two-way street; mood also affects how you perceive music. For example, I have always loved a recording by flutist James Galway of a classical piece composed by Jules Mouquet called “Pan et Les Oiseaux” (Pan and the Birds). It starts off quietly, with the occasional trilling of Galway’s flute conveying a vivid image of birds warming up for their daily concert as dawn breaks. As the flute gets louder and more continuous, I can feel the sun warming my face and see a flutter of wings fill the sky. The piece has always reminded me of my mother, who was an avid birdwatcher and nature lover. Since my mother passed away, more than ten years ago, I cannot hold back the tears when Galway’s “birds” take flight. The music has become inextricably linked with my mother’s memory.

Are you especially moved by certain songs, or enthralled by a particular kind of sound? Think about why. Your ears may have quite a story to tell.

Related Articles

• Soundings: A Contemporary Score
• Calming Music to Fly To

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Find Out More

• Dave Munger, “What We Hear, and How It Affects What We See,” Cognitive Daily, January 9, 2007
• “Link Between Fear and Sound Perception Discovered,” ScienceDaily, June 30, 2013

Read about Ed Decker.