Latest Issue of Science News

Scicurious

A peek behind the science curtain

Bethany Brookshire

Scicurious


Scicurious

Our taste in music may age out of harmony

As we get older, our brains may be less able to discriminate between harmony and dissonance

Symphony

In music, some notes ring together in beautiful harmony, while others rattle against each other. Our brains process consonance and dissonance differently, but the differences decrease as we grow older.

Sponsor Message

Music displays all the harmony and discord the auditory world has to offer. The perfect pair of notes at the end of the Kyrie in Mozart’s Requiem fills churches and concert halls with a single chord of ringing, echoing consonance. Composers such as Arnold Schönberg explored the depths of dissonance — groups of notes that, played together, exist in unstable antagonism, their frequencies crashing and banging against each other. Dissonant chords are difficult to sing and often painful to hear.

But they may get less painful with age.

As we age, our brains may lose the clear-cut representations of these consonant and dissonant chords, a new study shows. The loss may affect how older people engage with music and shows that age-related hearing loss is more complex than just having to reach for the volume controls.

The main mechanism behind age-related hearing loss is the deterioration of the outer hair cells in the cochlea, a coiled structure within our inner ear. When sound waves enter the ear, a membrane vibrates, pulling the hair cells to and fro and kicking off a series of events that produce electrical signals that will be sent onward to the brain. As we age, we lose some of these outer hair cells, and with them goes our ability to hear extremely high frequencies.

Another process also decreases with age: Temporal coding, the timing at which individual or groups of brain cells fire. Auditory neuroscientists Oliver Bones, of the Chinese University of Hong Kong, and Christopher Plack, of the University of Manchester in England, examined how temporal coding changes with age, and what that means for our perception of musical tones.

The scientists previously showed that this timing of neuron firing within the brain stem was associated with how people perceive consonant pairs of musical notes — harmonious and generally pleasing — or dissonant ones, which can be harsh and tense. The researchers reasoned that if temporal coding in the brain stem declined with age, the ability to distinguish consonance from dissonance might decrease as well.

Their new study included 28 participants under age 40 and 16 participants over 40. In one test, participants ranked pairs of notes played together on a scale of “very unpleasant” to “very pleasant.” They heard chords ranging from what’s called a minor second — two clashing notes only a half step apart on the scale — to the consonant perfect fifth — the first and fifth notes of a traditional seven-note scale — with all the two-note chords in between.

In a second experiment, Bones and Plack recorded the participants’ neural responses within the brain stem while they heard a consonant or dissonant chord. They used a technique called frequency-following response, which measures the response of a group of neurons to a sound stimulus such as a musical chord.

In young people, there was a sharp distinction in temporal coding in response to the two different types of chords. But this sharply defined timing became fuzzier with age: Older subjects did not distinguish as sharply between consonant and dissonant chords, the researchers report March 4 in the Journal of Neuroscience.

And that may explain a result from the first experiment: Older participants rated dissonant chords as less unpleasant than did younger people. They also rated consonant chords as less pleasant.

Even though these dissonant tones might seem unpleasant for young folks, Bones notes we probably can’t really enjoy music without them. He explains that we know a chord is dissonant only because it sounds different in comparison to a consonant chord. And that if you don’t have a perfect fifth to compare to a minor second, neither chord would sound as interesting — or, possibly, as musical. “If you didn’t have a sense of consonance you wouldn’t enjoy the dissonance,” he says. “It’s not that one is better.”

The results show that age-related hearing loss goes deeper than the loss of the hair cells in the inner ear.  “As we age and temporal coding in the brain declines, this might be the cause of older listeners being less sensitive to the difference between consonant and dissonant chords,” says Nina Kraus, an auditory neuroscientist at Northwestern University in Evanston, Ill. She says a deterioration in the ability to distinguish these chords “might lead also to older listeners tending to engage less with music.”

The participants in this study were nonmusicians, people who had had no musical training in at least the last five years. Kraus says that “it would be extremely interesting to see whether older musicians would also show a decline in both consonant preference and neural encoding.”

But there’s a lot more to musical enjoyment than an ability to distinguish chords. Just because older people might not be able to process the chords as clearly doesn’t mean they can’t enjoy the music. “A lot of what we like is the music we imprinted on in adolescence,” says Jennifer Tufts, an audiologist at the University of Connecticut in Mansfield. “My gut feeling is that those kinds of choices are influenced at a much higher level, a much higher cognitive level drawing on personality and training.” If you liked Jimmy Buffet before, you’ll probably still like him when you’re older. Hearing may change, but taste stays the same.

Psychology,, Neuroscience

Balancing the excitation and inhibition tightrope in depression

By Bethany Brookshire 12:17pm, September 25, 2014
A new study looks at how a balance of positive and negative inputs in the lateral habenula might relate to disappointment and depression.
Science & Society,, Physics

Banana peel slipperiness wins IgNobel prize in physics

By Bethany Brookshire 1:57pm, September 19, 2014
Cartoons taught us that banana peels make for a slick trip to the floor, but scientists decided to find out just how slippery they could be.
Psychology,, Neuroscience

Training the overweight brain to abstain

By Bethany Brookshire 4:30pm, September 16, 2014
A new study shows that brain changes are associated with a weight-loss behavioral intervention, but it may be a while before we can train our brains to prefer peppers over pork chops.
Psychology,, Neuroscience

In PTSD, a good night’s sleep means feeling safe

By Bethany Brookshire 4:08pm, September 12, 2014
Studies of PTSD in rats have usually focused on fear and trauma. But a new study in humans shows that learning about safety may be important as well.
Neuroscience

To study attention, pay attention to bats

By Bethany Brookshire 1:03pm, September 8, 2014
Studying how bats’ brains find prey using echolocation could have implications for the way human brains pay attention.
Psychology,, Health,, Evolution

Hypothesis on evolution of PMS attracts hostility

By Bethany Brookshire 3:14pm, August 25, 2014
A new hypothesis states that PMS is evolutionarily useful for making women leave an infertile partnership. But other scientists question whether the hypothesis is reasonable or, in fact, even necessary.
Biomedicine

Taking lab mice back to their roots

By Bethany Brookshire 4:12pm, August 19, 2014
Lab mice are incredibly useful for biomedical research. But they are also incredibly inbred. A new study shows that bringing wild mouse traits back could help uncover new links between genes and behavior.
Biomedicine

Clearing up anatomy with a see-through mouse

By Bethany Brookshire 4:30pm, August 14, 2014
A new method begins with a mouse or rat and ends with a transparent body, where details can be visualized all the way to the DNA. Here’s how it works.
Neuroscience

For neurons, birthday matters

By Bethany Brookshire 1:25pm, August 8, 2014
How brain cells make their connections during development still isn’t well understood. A new study shows that in the eye, a neuron’s birthday makes a difference in how it finds its targets.
Psychology,, Neuroscience

Addiction showcases the brain’s flexibility

By Bethany Brookshire 1:57pm, August 5, 2014
People with substance abuse disorders are not just chasing a high. Their brains are adapting to the presence of drug, evidence of humans’ impressive neural plasticity.
Subscribe to RSS - Scicurious