Giving children music lessons won't just introduce them to a world of rhythm and melody – it could also significantly improve their language skills.

While numerous studies have shown that learning an instrument can impact things like language ability, it wasn't understood if this was a side effect of a general boost to cognitive skills, or something that directly affected language processing.

Now, we are getting closer to an answer, thanks to a study of 74 Chinese kindergarten children, led by neuroscientist Robert Desimone from MIT.

"The children didn't differ in the more broad cognitive measures, but they did show some improvements in word discrimination, particularly for consonants," explains Desimone.

"The piano group showed the best improvement there."

For the study, Desimone's team – including MIT scientists and researchers from Beijing Normal University – recruited children from the Chinese education system, with the support of education officials who wanted to see how music learning might boost their academic results.

The 4- to 5-year-old Mandarin-speaking children in the study were randomly divided into three groups. One group received a 45-minute piano lesson three times a week, while another received extra reading instruction classes. The third group acted as controls, taking no extra lessons beyond their usual routine.

The classes lasted for six months, after which the children were tested on their ability to discriminate words based on differences in tone, consonants, or vowels. (In Mandarin, many words differ depending on their tone, with different tones giving words different meanings.)

The test results showed that the children who had taken piano lessons performed significantly better at discriminating between words that differ by a single consonant, when compared against the children who took extra reading lessons.

Compared to the control group, both the music learners and the extra reading group did better in terms of discriminating words based on vowel differences.

To get a sense of why these differences might be occurring, the researchers measured the children's brain activity via electroencephalography (EEG) and found the piano group exhibited greater sensitivity to tonal changes when tones were played to them at different pitches.

The thinking goes, the exposure to music lessons helped develop this tonal sensitivity, which in part explains their better verbal word discrimination.

"That's a big thing for kids in learning language: being able to hear the differences between words," Desimone says. "They really did benefit from that."

Perhaps more importantly, results of IQ, attention, and working memory among the three groups didn't show any significant differences, suggesting that the boost given by music instruction isn't a general cognitive lift, but something specific to language (and perhaps the tone-based elements of it).

Of course, we're only looking at a fairly small sample of kids here, and all of them were from a Mandarin-speaking background. Given Mandarin's reliance on tonal differentiation, the researchers acknowledge that might have influenced the results.

But it's also worth emphasising that the musical education helped these children outperform their peers in language tests – even beyond the results of kids who took extra reading classes, which is something that should make educators pay close attention.

"It looks like for recognising differences between sounds, including speech sounds, it's better than extra reading. That means schools could invest in music and there will be generalisation to speech sounds," Desimone says.

"It's not worse than giving extra reading to the kids, which is probably what many schools are tempted to do – get rid of the arts education and just have more reading."

The findings are reported in Proceedings of the National Academy of Sciences.