March 11, 2009 -- All those hours practicing the piano pay off big time by biologically enhancing a person's ability to quickly recognize and mentally process sounds that carry emotion, according to a new study.
The study, from Northwestern University in Evanston, Ill., offers a new line of evidence that the brain we end up with is not necessarily the same brain we started out with.
"We are measuring what the nervous system has become, based on an individual's experience with sound," Nina Kraus, director of the university's groundbreaking Auditory Neuroscience Laboratory, said in a telephone interview.
Kraus and a team of researchers attached electrodes to the heads of 30 people, half of whom were serious musicians and half of whom had no significant musical training. The electrodes measure electricity, "which is, of course, the currency of the nervous system," Kraus said. The study revealed two major differences between the musicians and the nonmusicians.
Musicians heard an emotion-packed, complex sound with an enhanced sensitivity, and they also were less distracted by simple sounds, according to the study, published in the current issue of the European Journal of Neuroscience.
"What we found in this study is both an enhancement and an economy of resources varies as a function of the extent of musical experience," Kraus said. "The more years the person has been playing an instrument, and the earlier the person began musical training, the larger the effect."
Although many other studies have tried to show the beneficial effects of musical training, the researchers said their findings "provide the first biological evidence for behavioral observations indicating that musical training enhances the perception of vocally expressed emotion." The findings have implications far beyond the world of music.
"The same neural transcription process that is enhanced in musicians is found to be deficient in some children with language disorders such as dyslexia and autism," Kraus noted.
The research suggests that something as basic as musical training may be a useful therapeutic device, along with other more traditional techniques.
"Quickly and accurately identifying emotion in sound is a skill that translates across all arenas, whether in the predator-infested jungle or in the classroom, boardroom or bedroom," said Dana Strait, a doctoral candidate in the music department and lead author of the study.
The researchers relied on an emotion-packed sound that has been used for many years by scientists around the world who have studied auditory processes -- the sound of an infant crying. That sound carries an enormous emotional load, but it is also a surprisingly complex sound.
Sound waves measured during the experiment show periods of relatively mild emotional content in the sounds from the baby -- almost a straight line on a chart -- punctuated with brief bursts of complex sounds that vary in intensity, frequency and strength.
The participants, wearing earphones, sat in front of a monitor showing nature films with subtitles. Every now and then, they heard the sound of a baby crying through the earphones. The electrodes measured the stimulus -- the baby crying -- and the response of each participant.
As expected, the musicians had an enhanced ability to pick up on the emotional cues of the sound. But the researchers were a little surprised to learn that the musicians were more attuned to the complex sounds -- those carrying the most emotion -- than to the less significant "periodic" sounds of crying. That allowed them to devote more resources to the important sounds and virtually ignore the sounds that carried little emotion.
Who We Are, What We Have Done
That reflects an increased economy of resources -- don't waste energy listening to something that says nothing.
"Enhancements, reflected by larger time -- and frequency -- domain response magnitudes, were most evident in musicians' responses to the most complex portions of the sound, with economy (smaller amplitudes) seen in their responses to the periodic portion," the researchers report.
The findings might seem open to the chicken-and-egg debate. Did the musicians perform better because they are naturally more sensitive to sounds, and thus more likely to study music? Or did their nervous systems change because they were exposed to music for more than a decade?
The researchers feel confident the correct answer is the latter.
"With musician studies you always wonder if the person was just born with a more accurate sensor," Kraus said. "And there's probably an element of that. We're all a combination of nature and nurture."
But the fact that all the musicians performed so much better than the nonmusicians clearly shows that the study of music -- not an innate musical aptitude -- literally changed the way the musicians' brains processed sounds, the researchers concluded.
"Our results provide evidence for a subcortical role in the processing of emotional cues by showing that auditory brainstem responses to emotionally salient vocal sounds are dynamic, shaped by life-long, multisensory experience with auditory signals," the researchers note. "These responses are not hardwired but malleable with extensive auditory training."
In other words, we aren't just who we are. We're also what we have done.